> networks and servers are will only get faster

this isn't an argument for SSR. In fact there's hardly a universal argument for SSR. You're thinking of a specific use-case where there's more compute capacity on the server, where logic can't be easily split, etc. There are plenty of examples that make the client-side rendering faster.

Rendering logic can be disproportionately complex relative to the data size. Moreover, client resources may actually be larger in aggregate than sever. If SSR would be the only reasonable game in we wouldn't have excitement around Web Assembly.

Also take a look at the local-computation post https://news.ycombinator.com/item?id=44833834

The reality is that you can't know which one is better and you should be able to decide at request time.