What is Berg's legacy, and what would it have been had he lived into his 80s ?

   Had he lived as long as Strauss would  he have made atonal/12-tone music "consumer friendly" and main stream, at least to a degree? Would old  Alban , writing in 1970, be pushing forward or would be churning out his own version of "Metamorphosen"

    In the war would he have acted as W A Hartmann, left Germany or changed his style to fit in ? Was he as great or greater than others of the 2nd V S  or does the listener friendly aspect of his music lessen its worth, any thoughts?

Rather than Britten softening Berg up, maybe Berg would have encouraged Britten to develop his earlier flirtations with pseudo-serialism and to enter fully into the modernist world...
Do I remember rightly that Walton was also interested in studying with him? Also, don't forget that his path crossed with Shostakovitch but they were both too shy (?) to talk music.

Now, this is all from memory and therefore might be defective, but I seem to remember that he was in the process of making plans to leave Germany and join Schoenberg in California when he was stung by that fatal insect.

Berg often gets a rough deal (from head-banging p-m modernists like me) for being accessible and user-friendly, when there is a great deal of complexity in his compositional method. Many of his methods of manipulating the row have clear parallels with many contemporary composers' pitch manipulations and his rhythmic ideas are potentially more influential and flexible than anything that the total serialists derived from Webern.
You can argue that Schoenberg's earlier formal innovations were too closely linked to text to have anything more than a limited application and influence, and that the later forms did not develop the archetypes that were embodied in them. You can also argue that Webern's use of formal types was artificial in a manner that seems to be in contrast to his organicist vision of his music. Berg's methods seem uniquely placed out of his time. Had he lived, I think that he could well have overshadowed Schoenberg, and that he may well have kept the connection to the music of the past in the forefront of modernist thinking even after the war.
Possibly.

I love the way that each of the 2nd Viennese have something to teach us. We diminish their worth and the worth of their music when we consider them as a lumpen mass.

I've always found much of Berg's music difficult to get on with - the 12-note stuff in particular. My interest in serialism was encouraged more by those pieces of Webern and (a few by) Schoenberg which seemed infinitely more approachable - and - Skalkottas.

Describing Berg's references to tonal harmonic idioms as "user-friendly" does his work a disservice, I think, and it certainly does a disservice to the music of Schoenberg and Webern, which I presume is supposed by implication to be "user-unfriendly". There's a difference between listening to music and using computer software, after all.

Good point Richard.
I first heard the concerto when I was 16. One of my Dad's friends played in the local symphony orchestra and they were playing it. She recommended that we attend a rehearsal so that we could 'get into' the piece before the concert. We did and by the time I got to the concert, I was hooked. It's not the tonality that makes it accessable at all it seems to me, rather that it attempts to be expressive in a manner that is (almost unprecedentedly in his output) unmediated. It can come over as a little heart-on-sleeve at times, but perhaps we're all a little too familiar with the programme (both 'official' and 'secret').
I'm not really familiar with the formal aspects of the concerto. Keep on meaning to look into it but there's always something else. Also, I think that the Kammerkonzert is a work that I should really study. Next year, next year.

I can't resist making an attempt at this thread...

Firstly, I can't help thinking that much of Berg's early music (up to and including the Piano Sonata) is already more polished, rich and allusive than the equivalent early works of Webern or Schoenberg. To me, that suggests a composer who had much to say, had a language in which to say it (because those fingerprints DO recur throughout his output) and just needed experience.

Schoenberg composed much indifferent music in his early years, took off with Verklaerte Nacht and then pushed forward the bounds of expressivity until he found A Method. (ie serialism). From then on, I feel there is an aridity about his work which both Webern and Berg avoid, Berg by a creative/ selective use of serial techniques, Webern by his marvellous ear for instrumental colour. (Not that I dislike the later Schoenberg, just that I can't take much of it in one sitting and it doesn't particularly touch me.)

Berg seems to me an exemplar of the composer whose methods and technical expertise lie beneath the surface as a means to an end - the end being communication and expressivity. I suspect the perceived relative ease or difficulty of different pieces would be incomprehensible to Berg himself, and whilst there are passages in Lulu that I find difficult and other pages that are achingly, painfully expressive, my gut feeling is that Berg is, in his own way trying to communicate with every note he writes. The balance is different in the Violin Concerto, but the way the Carinthian tune comes in and out of focus in movement 1b is for me doing just what so much of Lulu does.

If he had lived, I guess the way his career would have developed would have depended upon his response to World War 2 - we might have had another Wozzeck-type work, or something (if possible) even more bleak and hopeless.

As for Britten - I think he would have been a better composer for studying with Berg - less content to leave scaffolding in place of a real piece of music.

I wonder whether a composer like Dallapiccola is Berg's true heir?

Il canto sospeso, Sara dolce tacere - yes!

Also Maderna, Donatoni and Berio - the Italians have it...

The composer who to me most clearly stands in a lineage from Berg is B.A. Zimmermann. His opera Die Soldaten so clearly builds upon the models established by Wozzeck and Lulu. And, whilst stylistically quite different, the Requiem (one of the greatest of all post-war compositions, in my mind) shows the possibility of integration of diverse material of which Berg was such a master (so so different either to Stravinsky or to countless post-modern imitators of today). Rihm in particular also seems very much in a Bergian tradition, and I can see what people mean about Nono as well.