On October 2, one of the members of the Florida Constitution Review Commission said she will sponsor a change to the Florida Constitution pertaining to election law. Currently, Florida has closed primaries, except all registered voters can vote in the primary for a particular office if all the candidates for that particular office are from the same party. The proposed change would amend that, to say that “all candidates” only refers to candidates who filed to be on the ballot, not write-in candidates. See this press release from the Commission.
In the next few weeks, committees of the Commission will evaluate this idea. If it passes through committee, then the full commission will decide whether to adopt the idea. IF the full Commission adopts the idea, then the idea will appear on the ballot in November 2018 as a proposed Florida constitution change.
http://flcrc.gov/Proposals/Public/700396
If someone wanted to keep a primary closed, they could simply fund a minor party or independent candidate. This has been done in the past. Remember when there were some Green Party candidates who the party officials did not know, and the lawsuit the Green Party was represented by a lawyer who normally worked for the Democratic Party.
In 2016, 75 of 160 legislative seats (47%) were uncontested, or only had a write-in candidate.
Florida should adopt the Top 2 Open Primary (proposal 100117).