I once discussed with @CaptainShadow similar scenario.
Though Tudor thought didn't appear in our scenario and that is a solid suggestion. Actually if Henry wants to promote Tudor, Tudor is marrying Anne of York, as Mortimer claim would pass to her.
The age difference is not so big - 9 years, there were bigger age differences back then.
Yeah, it does make a lot of sense, though it would require Richard, Duke of York’s agreement and I figured that Anne would still marry Exeter since butterflies won’t begin to affect things until the late 1440s and 1450s, though Exeter could be killed off so that Anne can marry Tudor. The marriage is beneficial for the two of them (Anne gains a high standing place at court and Edmund get’s a rich wife) and would be quite interesting. I do have a similar idea for a TL where Anne is Richard’s only child who marries Edmund in 1453-ish and gives birth to his only child, Richard Tudor, who later becomes the ‘Yorkist’ claimant.
If female March has somewhat similar personality to her OTL counterpart she could marry Henry Beaufort, Somerset's heir since OTL male March and Somerset shared a close friendship (suspected of being lovers even) and if ITTL March is female...big daddy RoY can catch Henry B and female March doing the banging.
And marriage would be only option out.
Female Edward IV (Cecily?) and Henry Beaufort would be an ironic match, especially if they enjoy a similar BFFs for life, followed by breakup they did in OTL. Another fun alt pairing would be female Richard III and Henry Tudor (if he still exists)!
Would the feudal Duchy of York be reverted back to the Lancastrian Crown?
And if Henry VI does have issue IOTL*, would he bestow it on one of his would be sons?
* That's if he have more children besides Westminster.
The Dukedom of York would revert to the crown but would likely be given to Anne’s husband later down the line. I imagine Edward would remain Henry VI’s only child here, but who knows?
No I am fairly sure Girls could inherit lands but he could marry off the heiress to a hypothetical second son which achieves the same result
The Duchy of York is a male-line only Royal Dukedom. If Richard only bores girls, his Dukedom would be crown property upon his death.
The title itself would be forfeit but lands of RoY would pass to his daughters.
What
@Zygmunt Stary said, the Dukedom would revert to the crown, but the lands and possibly Earldoms of Richard would be divided up among his daughters.
Another things, females can inherit titles and estates if they in question are not male-line only.
True, not sure which of Richard’s titles were entailed in the female line though.