There isn't really anywhere, bar the old C&W site which is being done plus a couple of brownfield sites, to develop near Bletchley station. Though I suppose they could close the cement works and develop that - I had heard a suggestion that one option was to build a new multi storey station car park there and build houses on the existing one. Bicester has also gone from a small town to a large one in the time I've lived anywhere near it - quite a transformation really, and a bit New Town esque.
I'd look to build eco-villages centred on Marston Vale stations if it was me.
I also suspect Winslow will grow in a very Bicester like fashion.
The whole East-West Arc is potentially available for development- subject to government 'enthusiasm'/ NIMYism/ food security and projected changes to planning processes!
I can foresee a likelihood as the arc 'takes off' of potential demands for trains from a variety of 'heres' to a number of 'theres'- bearing in mind capacity issues related to London's Thameslink and Manchester's Castlefield Corridor, choices may need to made of priorities. For me the first such decision will need to be how MK is to be served. A frequent tram-train shuttle to Bletchley must be quite a strong contender.
The Oxford end must also be a constraint. There must be continuing and possibly increasing demand for Oxford- Marylebone services, constraining the capacity east of Bicester. North- South services 'snaking' across using EWR for part of the route will similarly restrict paths.
There may a case for something East-West at more like Tube/Metro frequencies with some kind of 'co-ordination' of North- South services (somewhat in the way that I seem to recall was hoped for at Birmingham New Street as the Heart of England when the WCML was electrified?); I can't see it being possible to 'guarantee' any connections.
Still the best to hope at this time is to get trains running (and reliably) somewhere soonest, for the pre-election photo-opportunites.
No. It is a regional service which will be used for many different overlapping local journeys, a bit like EMR's Liverpool to Norwich.
Maybe something like a Bristol or Southampton - Norwich if paths exist south of Oxford?