Depends on the outcome of various planned infrastructure schemes in my view. If NUCKLE sorts itself out you could speculate on two for Coventry Nuneaton, another one for Leamington Coventry off the back of Kenilworth and maybe two for the Marston Vale if they went for that, so five maybe six if they wanted a spare. Another wild one could be if a bidder brought back Wolves Walsall direct services, that could bring you to seven. It could even just be the one for the trial and that is it.
Once Oxford's signalling is sorted out, but before E-W is complete...
I could imagine a set of 230s running a short-term OA franchise Bicester Village-Oxford every 30 minutes - thus effectively giving Bicester Village & Oxford Parkway a service every 15 minutes into Oxford.
It's what the service will be post E-W, so why not start it now?
At a guess at the layout of the signalling, units will be able to proceed past the Bicester chord to clear the line, then return into Bicester.
Very handy for Long Marston "depot"
Might even allow for the odd extra passenger service between HYB and OXF in lieu of an ECS.