I read in the Express (online) a few weeks ago that they may not expand next season. There was some talk about merging the PFL teams with the Super League teams into one one league. The opposition to that lay in the fact that there are certain financial criteria etc that must be met in order to qualify to be a member of the PFL. The minimum financial criteria rules are there to ensure that players can get paid by the teams they play for etc.
Anyway, that's basically what I remembered from the article...