It's not quite "all" up to the BON; it's also a matter of individual employers' policies, even if it is allowed legally. The BON isn't going to make
anyone employ someone at a lower level of licensure, and a lot of facilities/organizations just prefer not to do that because of the unclear liability issues.
OP, if it's a matter of continuing at a current job, you may want to check with your current employer about what their position will be at the time that this becomes an issue. Quite a few people have posted here over the years that they abruptly got dropped from their current employment as soon as they got their new license, without any prior warning (because it was the employer's policy to not employ people at a lower level of licensure). If that's going to happen, it would be nice to at least know about it in advance and be prepared for that.