Warren looks like she's going to get 10 to 12% of the vote, and I don't know what the cutoff is for delegates. There are 89 delegates from Washington State, 34 of them have been allocated so far to Biden and Sanders, and my hope is that my vote for Warren will be carried forward by a delegate for Warren to the convention.

I'm embarrassed to say that I don't know what the threshold is for delegates. And I'm a political junkie.

to get any delegates. Delegates are awarded by districts or statewide. So, it is possible that she might have 15% or more in some districts, and might end up with a delegate or two that way.

That 15% rule is across the board including at the convention. Any nominated candidate at the convention has to get 15% or more delegate votes on the first ballot, or they are dropped from the next ballot. Most likely, such a candidate would not be nominated to be on the first ballot, though, although that is a possibility.

In most cases, those candidates issue a non-binding instruction for their delegates to vote for the presumed nominee unless there's a law to the contrary in their state.

I was a delegate to the Philadelphia convention and saw how the process works. One key item is that under the rules, a candidate cannot be put into nomination without 300 delegates. https://democrats.org/wp-content/uploads/2019/02/2020-Call-for-Convention-WITH-Attachments-2.26.19.pdf

....it's unclear though.

I don't think it's going to be an issue, though. Biden will easily get more than the required 1991 by mid-April.

I have not looked at the convention rules this year. They are not finalized until the convention votes on the rules.

Biden currently has 901 delegates, according to:

https://www.thegreenpapers.com/P20/D

Sanders has 737, according to the same source.

If that happens, it is over.

I was a Clinton delegate to the 2016 convention and I had fun reading up on the rules. All delegates are free to vote for anyone they want at the convention and this includes so-called pledged delegates or super delegates (PLEO and automatic delegates). Candidates can protect themselves by vetting delegates. Each candidate has absolute approval right over their pledged delegates. I know that I was vetted and I helped vet other Clinton delegates. At the Texas state convention in 2016, the sanders campaign removed a delegate elected by his senate district caucus because that young man would not tell a sanders campaign official that he hated Clinton. That young man was removed but got to attended the national convention as a guest of the state party.

The candidates who have withdrawn still get to approve and vet their delegates. That means that these candidates should work with the Biden campaign to select delegates who agree with that candidates choices. This means selecting hard core/real democrats who are actual members of the Democratic Party and who will do what is best for the party. I have been working with my county and state party for a very long time which is how I got elected as a delegate. Normally it takes years of hard work inside the party to qualify as a national delegate. These people are not going to do something that is against the best interests of the party.

Please note that these candidates cannot put their name into nomination without 300 delegates. I suspect that the Biden campaign will be taking steps to vet or help the withdrawned candidates vet their delegates. I am active on Lawyers for Biden and will be making some suggestions here later.