The only routes I can see M2 vulnerable on at the moment are BHD (where BE have a huge presence) and LBA which is may be in the scope of BE for further expansion.
It'd be interesting to see what happens on this score. Flybe ditched both of these routes when the original Q200/300's were returned. The BHD route was cancelled following the cancellation of the BHD-IOM-LCY route. The LBA route was handed over to Eastern I think, at the same time as the BRS route was also removed.
Jersey European used to have a significant presence in IOM, however this was all but wiped out when the fleet was concentrated on the much larger Q400. Flybe really only came back to IOM following the acquisition of BAConnect. I'm not so sure that Flybe would attempt to place such a large aircraft on either the LBA or the BHD routes but funnier things have happened.