Which is, essentially, what fivethirtyeight is doing as well. They are not considering the eventual swap of delegates after candidates drop out. Those delegates will of course be reallocated, but that's outside the purview of the model, which is just calculating the expected number of delegates each candidate will earn through the statewide voting/caucusing process. Really, it's the only way to do it at this point. The calculus of a constested convention is an entirely different animal and impossible to predict at this stage.
I still think Bernie's best hope to maintain a plurality will be keeping all of the moderates in the field as long as possible. As those candidates drop out, the question then becomes "can he win a 'head to head to head' with one moderate Dem and Bloomberg?" As long as there are 2, 3, or 3.5 (counting Warren as a 0.5) moderate/establishment candidates in the field, they will ciphen enough of the vote from each other that many won't be viable in a state, while also hurting the chances that a moderate/establishment candidate outdoes Sanders. So Sanders and that one other candidate will get a lot of the delegates, even with a relatively small share of the popular vote.
Basically, it would be a continuation of what we've seen in Iowa and New Hampshire. Sanders got around 26% of the popular vote in each of those two states.
Buttigieg has gotten around 25%. But each has gotten ~33% of the delegates, because Biden/Klobuchar/Warren have kept two of the moderate/establishment candidates below 15% (even though they have combined for about 40-45% of the popular vote. If that ~40-45% of the vote that those three have gotten in the first two states gets starts getting reallocated among Sanders/[mod/estab Dem]/Bloomberg in future states, it has dramatic implications. And likely in the favor of the moderate/establishment candidate.
So it's in Sanders' best interest to keep those mod/establishment Dems viable as long as possible, because it weakens his nearest rival AND it inflates his delegate count relative to vote support. Which is another reason why I think we'll start to see the DNC pressuring some of their career Dems out of the race pretty soon. If they can get it down to Buttigieg and one career Dem, they can probably figure out quickly who is viable (or if Sanders gets enough of the dropout support) through the future states' results.