Js and WebAssembly are both quite compact, I don't think many apps will be more than 10-100 MB. Of course they may contain extra data such as images for the ui or translations in text files but those can be downloaded on the side and cached.
the thing is, these apps are already multi-GB when compiled for x86/x64 platforms.
and please, please whoever is doing it - the performance will be crap compared to instant desktop. you can't get around it. it doesn't matter how powerful PC or how fast internet connection will be. I see it on gmail with my 100 mbs connection all the time, PC being quite performant one. when it was 800 mbs nothing changed.
I can accept it in gmail/facebook/whateva where expectations are low, but for anybody doing serious work in these tools, it will be frustrating, annoying experience for foreseeable future. As an complement to desktop app (say on the roads), why not. But nothing more
