Tons of people could make strong runs, none will be serious contenders. The way the Democrats work is too much solidarity among the donor community, theres just no enough cash to spread around.
Isn't that what people used to say about the Republicans? That they always anointed a single person as their establishment champion? That seriously broke down in 2008, when consensus on who the establishment frontrunner should be didn't materialize early on, and then this broke down further in 2016.
No, I dont think thats the case about the GOP. The GOP has been a "next in line" party but thats more the voters than the donors, we've seen plenty of real candidacy challenges among republicans with major funding.
Democrats tend to have less of the "sugar daddy" (no better way to put it) effect of a single or handful of major donors backing a lesser candidate. What you see often is democrat donors tend to get in groups behind two, maybe three candidates. When we see an out of the blue candidate they are often backed but hundreds of small donors (bernie and howard dean come to mind) or come with a powerful fundraising network behind them (Obama and Bill Clinton). And with the exception of Clinton we havent seen the race fall into anything but a 2 horse race with donors quickly lining up behind one or the other. I also tend to think 92 would have happened quite a bit differently if the primaries had started later as Cuomo or Gore would have gotten in if Bush hadn't been riding the approval rating wave he had. Cuomo probably clears that field pretty quickly with the donors.
I think the best way to put it is this: almost all GOP donors pick a horse early and get in the race right away, which is where we get like 500 candidates funded by only 1 or two people, where as on the dem side only a handful of donors get in early and the rest jump in after Iowa behind one or another candidate.