I think Virginia wants to encourage lots of trips that start someplace in Virginia and end at WAS, such that no matter how frequent the trains get, they'd rather have to fill the train (and have a big train to fill) at low fares.
I don't think there's been a problem filling Virginia-WAS seats such that they turnover at WAS and then balance what Amtrak wants to sell WAS-northward. So while I love the idea of hourly ping-ponging, if they ever get to hourlies, they'd probably want high-capacity trains anyway.
And given that slots across the Long Bridge and on CSX/NS will always be valuable, I don't see them ever trading down to smaller trains as the price of being more frequent.
Meanwhile I'd like to show where Virginia could be adding more stops (marked in an X) to complement its existing stops (marked with ~15 mile bulls eye)
From Left to Right you have
Bristol X (BUS I propose as an extension of the virginiabreeze.org bus, simply tagging a 2 hour extension on the start and end of every existing bus)
VaTech Blacksburg-Christiansburg (NRV RAIL but is a Bulls Eye thanks to the virginiabreeze.org bus, but let's wait 'til the bus proves "beyond RNK" demand)
Bedford X (RAIL INFILL they've asked for an infill, I think they should get it, if only as an "easy parking" ploy)
Gretna X (RAIL INFILL 'zactly halfway between Lynchburg & Danville
Winchester X (BUS Will probably get a Route 7 Bus Winchester-Berryville-Purcellville-Leesburg-Ashburn-Dulles which ties to the Silver Line rather than fight traffic into DC, but it could do HOV all the way to West Falls Church)
Ashland/Kings Dominion (RAIL INFILL halfway between Richmond and Fredericksburg)
Bowers Hill VA (RAIL INFILL @ I-664, I-264, & US 58) Alternate Downtown Suffolk VA