So far alts have not really fared all too well during bear markets either though. Only few bring something new to the table. Assuming Bitcoin dies, what makes you think that alts will fare better? Apart from Stablecoins, which face challenges of their own, alts too are speculative cryptocurrencies. Arguably even moreso than Bitcoin.

While I disagree with your sentiment that Bitcointalk should focus more on alts, I think that more serious discussion of concepts that possibly go beyond Bitcoin is something I'd definitely welcome. For the most part this seems to be covered by the Development & Technical Discussion board, although it seems that some threads end up there for the lack of a more fitting section ie. what I assume would be roughly the sub-board you had in mind.