That makes sense with regards to the Aragon girls, but I wonder if Germaine will remarry if such an act will almost certainly cost her her kids and be under wild protest from Juana, who won't be a huge fan of her stepmother simply for the reason that Ferdinand married her to deny Aragon for Juana. Juana won't let her half-sisters overseas and I could see Germaine viewing her presence as the last line of defense from Juana deciding to remove her father's second family from the court by suggesting they all take the veil or exist as spinsters.
As for Mary Tudor, one thing I was considering was having Anne of Brittany having her stillborn son in 1503 and her miscarriage in 1505 be healthy boys, making Louis XII less in need of an heir and Anne more likely to survive (as I can see her cutting off sexual relationships in the name of health) making Mary unnecessary, unless she's marrying Francis as an insurance policy, and even then I still see him marrying Claude.
The reason Ferdinand becomes Maximilian is I can see Ferdinand II still trying to pull the "Juana's crazy and I need to assume the Regency" card because he wants the political power and thinks a pregnant Juana's an easy target. That plus the persistent rumors that her dad is already exploring the marriage market to game her out of Aragon means that by the time the baby is born Juana is angry at her dad and names the baby after her father-in-law as a sort of screw you to Ferdinand. Does that seem too OOC for Juana or would it make sense?
I'm not sure. Although it might be one of the only choices she has with both Phillip and Ferdinand out. Then again, there is very little on whether the two of them actually had a relationship since Maximilian ruled from Austria before her mardiagw, as Phillip took over for him in 1494. And Maximilian didn't really do much for Juana, even when she was being accused of being mad.
A possibility for another name might be Juan, which was her brother's.