Here are the states where Biden could win 100% of the delegates.

[Gothmog]

9. If we can hold sanders to under 300 delegates, his name will not be put into nomination

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

Nomination of the Democratic Candidate for President: The Permanent Chair shall receive nominations from the floor for the Democratic candidate for the Office of President of the United
States in the following manner:

a. Requests to nominate a presidential candidate shall be in writing and shall have affixed thereto the written approval of the proposed nominee and the name of the individuals who shall be recognized to make the nominating and seconding speeches on behalf of a presidential candidate and shall be delivered to the Convention Secretary at a location as specified by the Secretary no later than 6:00 p.m. of the day preceding the day designated for the commencement of presidential nominations.

b. Each such request must be accompanied by a petition indicating support for the proposed nominee signed by delegates representing not less than 300 or more than 600 delegate votes, not more than 50 of which may come from one (1) delegation. A delegate may not sign more than one (1) nominating petition for president and for vice president. Pledged and automatic delegates may sign the petition.

I signed the petition for Clinton in 2016 to put her into nomination but we have over 170 Clinton supporters in the Texas delegation.

If sanders is frozen out of enough states due to the 15% rule and remaining non-Biden delegates are split among several candidates, there is a chance that sanders may not reach 300 threshold