If you're not expecting to need fancy client side stuff, does next.js give you as good a server side development experience as Django/Rails/Laravel? At that point, it would seem worth it "just in case", as you suggest, but in the past when I looked at it, the SSR stuff still felt a little cobbled together and experimental. I would love to hear from someone with firsthand experience switching, though!
I think Next has a great DevEx, but I'm just using it for some projects as a solo dev without a ton of traffic so perhaps there's some rough corners I haven't experienced yet.
I do think they are going down some risky paths where they do things like rewrite your code files depending on whether you're on server or client, and in general with "framework-defined infrastructure" where if you write certain functions the framework "knows" that it's supposed to be on the server or in a background job or whatever. But so far I've gotten the benefits without the drawbacks, though I might be jynxing myself.