Isn't that already happening? Plenty of news sites are already fat apps, when you think about how much code they load to only deliver static content and maybe support comments, very little of the code being useful to end users.
I see where you're coming from. I have, however, tested a couple of news sites (e.g. BBC, The Guardian) while using an add blocker and the results are very interesting. The "amount of news" is nowhere near the "amount of adds". Without the adds, the news websites (some; I obviously couldn't test them all...) have a decent "size" and load quick enough.
When cnn etc are wasm apps,good luck blocking ads.