People who don't like Trump or the GOP don't OWE the Democratic Party anything. There's a difference between being a "big D" Democrat and a "small d" democrat. If the Party wants "small d" votes, it has to earn them. In 2024 it didn't. If you recall, Biden promised a vaguely progressive agenda in 2020 (free community college, minimum wage increase, child tax credit, the John Lewis Voting Rights Act, Medicare expansion into dental, etc.), only to see such things never so much as introduced because of opposition from "moderate" Democratic Party members in the House. If you recall, Democrats had the majority in both Houses, and the Republicans had no say whatsoever. Come 2024, the Harris Campaign's response was to make only the vaguest promises (support for abortion rights without specifics on how, some sort of credit for first-time home buyers and not much else) while instead courting disaffected Republicans (as exemplified by everyone's favorite neocon and coal mining advocate, Liz Cheney). The voters response was to stay home. That was predictable - or should have been. If you want to attract voters to vote FOR you, you need to tell them precisely how you're going to make things better. The Harris Campaign didn't; they seemed to expect that everyone would vote AGAINST Trump. It didn't work. I seem to remember the 2016 election being much the same with a similar result.
Actions since the election by the Party's establishment politicians from Schumer to Nadler to Cortez Masto to Cuellar have demonstrated to anyone paying attention (which is probably some fraction of that 90 million) that nothing has changed. Moreover, the reaction of the Party establishment to David Hogg's suggestion that dead wood be replaced have been largely hostile, suggesting that the establishment thinks what "we" need is more of the same.
Given where the Party is right now, and I can't see the establishment politicians giving up, I wouldn't expect the number of non-voters to go down anytime soon, nor would I expect much support from the non-voting citizenry, because the Democratic Party is (for the most part) not earning anything. I'd expect the numbers of non-voters to grow.