The answer to this can be straight: No, people will not upgrade. The rational answer.
But compare this question asked in 2015:
- Will Bitcoin community increase it's block size if and when the scaling capacity needs upgrade and needing to upgrade to bigger block size than 1 MB?
The rational answer would have been: Yes.
But what happened onward was a lot of divided community, debates, technical war through all possible ways, tx spamming, papers, research, biases boost, marketing, opinions etc.
The normal user who isn't well informed on what this whole technical thing doesn't understand what is right and what is wrong.
Ultimately, Blockstream hostile takeover. And divided community settles with Segwit solution. A solution of conditional size increase, to which the community was further divided to support or not to support along with 10s of other options they were already divided on which all didn't make to final solution.
If that experience actually plays like that in future, we can not for sure say all community voices will be heard in fair way. Whoever will be taking control of most influential resource, be it developer, marketing, maintainers, overall narrative shaping will shape the future of such sensitive matters. And for sure such sensitive matters will arise and things will look tougher and tougher as Bitcoin keeps riding ahead in the world.