Ethereum

With RaaS providers making it cheap to manage a rollup for you (few hundreds $/mo in the future) and easy to deploy (a few clicks), I think we'll have a Cambrian explosion of rollups soon... But then the hype will die down, many will fold, and over time we'll converge to a number of rollups, Z.

What do you think Z is?

I would have a slightly different perspective, in which indeed we would have an explosion of rollups, but we will not shrink that much, as rollups will become more and more specialized to serve a very specific niche of applications, nice thoughts! 100 $DEGEN

As long as a rollup can serve a niche better than a general one, it's all a matter of "product market fit", I think the real question here is, how many niche use cases will have enough demand to survive? On each of those, I believe we can still have from 1 to 3 major players, 100 $DEGEN

I think it depends on the magnitude of the hype around them. 
Hopefully it doesn't get to this, but think about all the teams who launched NFT collections during the 2021 bull market, what % of them are still around?