OK, other than my incorrect excitement about an 0139 Euston-MKC on a Saturday (still an 0200 bus unfortunately) here goes.
First reaction is - I like this.
Euston standard hour departures (all day including peaks) are:
xx09/xx39 Harrow, Bushey, Watford Jn, all stations to MKC (this means Cheddington gets 2tph during the day, not 1tph)
xx23/xx56 (Watford - xx23 only), Leighton, Bletchley, MKC, Wolverton, Northampton, stations to Birmingham
xx24/xx54 Tring semifast (not Bushey, Apsley, Kings Langley)
xx46 Crewe via TV, first stop MKC
These seem to be the same all day, plus a few fairly random looking peak extras, including a 1704 Tring semifast, a 1734 Bletchley semifast, a 1720 and 1819 WFJ-MKC-NMP (The Master Cobbler I guess?

), 1806 Bletchley semifast, 1834 Bletchley semifast and so on.
Seems a similar situation in the other direction, with Bletchley getting two fasts all day which is a considerable upgrade, I guess recognising that the station is soon, with EWR, to gain a more important role. The old situation of Tring stoppers starting back from Bletchley in the morning (I like these trains) has remained.
Sundays the pattern is very slightly different but broadly similar in concept:
No Trings
xx21/xx52 all stations to MKC
xx22/xx56 Birmingham semifast
xx45 Crewe via TV
Marston Vale has gone all Takt on me, 0515, 0642 then xx45 until 2045, then 2132. The other way 0615 then xx47 right through the day until a final 2238 (10 minutes later than now). Arrivals at Bletchley xx28, with no change to running times (surprised they didn't increase it a bit to deal with the slow doors so guards can continue to do revenue).
Connections wise the xx28 arrival gives you an xx39 to MKC and xx40 to Euston fast, which is pretty good. Northbound the xx45 departure isn't bad either assuming Bletchley is a standard 5 minutes which it looks like it is from the eNRT: xx31 fast from Euston, xx34 from MKC, xx38 slow from Euston, xx39 fast from Brum.
I think that is all a really neat job and a definite upgrade for Bletchley (particularly the MV, which almost looks like it's had SBB set on it with those nice connections - it basically arrives, then a full cycle, then departs), though I can see that the people of Northampton may like it a
bit less, though in the peaks they retain their fasts.
I'll let someone else do Avanti and St Albans, though I can't see any great surprises in there, and I'd not be confident Avanti will be running what they claim by then anyway! One "set down only" at MKC southbound in the peak (I guess they expect that one to be particularly busy - it's the 0721 arrival at MKC from Manchester, with the 0727 from Lancaster just in front) but otherwise it appears Avanti are, unlike VT, happy for the additional commuter revenue.