I understand that such a move is likely. There is no chance of a 135 for at least 18 months and frying pans and fires springs to mind.
Both Thames Valley and Yorkshire have been trying to cut costs as the AA money runs down and moving to another supplier is a classic way to achieve this. Trying to operate a new aircraft is far harder than and old one. Looks good but the repayments can cripple.
If TVAC is to change aircraft I think they may well return to their humble beginings.... its cheaper.