Despite what people have said upthread, there are no "Richardians" or "Edwardians"
There are. Both factions still exist.
I think one on the northern cities(York IIRC) went into mourning post-Bosworth,and, at this point of time, even a peasant uprising has a good chance at succeeding because:
A) The mercenaries have been dismissed
B) The southern lords won't give a sh**
C) Most of the northern lords are Ricardian/Yorkist,atleast nominally, so they can cause massive upheaval if they so choose.
This will allow us to kill off semi randomly:
A) EoY
B) Strafford(OK, he's a kid in 1485, but ~1500 he will be in his mid 20s, so that can be taken into account.)
C) Jasper Tudor (Obvious Target)
D) Elizabeth Woodville (If it's Ricardian)
Possible(Probable!) rebellions:
A) Perkin Warbeck
B) Lambert Simnel(maybe even the real one can do the same)
C) John De La Pole(He can rebel on his own, he's able enough)
D) Richard of Eastwell(If he can get support)
E) John of Gloucester (same as his maybe half-brother)
Queen Regnant Margaret ain't gonna happen, for the same reasons you have stated.
What's stopping the Edwardians from leaving Tudor? They'd rather have one of their own self/son married to her.
Jasper won't live long enough to leave legitimate issue, he didn't even have legitimate issue IOTL, who's to say he'll have some ITTL.
The bargain can be kept by making her consort, but post-Tudor, the Edwardians/Woodvilles are in a stronger position than the Lancastrians, who's to
they'll keep their part of the bargain?