Seems a bit unfair that Maxie was expected to foot the bill for all the inherited debts (except for Hungary) on his side of the family, and yet his brothers got off scot-free. The silver mines (not the Bohemian ones) I'm thinking of would've been in one of his brothers' territories weren't they?
I remember reading that Matthias sort of turned himself into the family-pariah when he got involved in Dutch affairs, so I don't think his relationships were that good to start with.
From another thread on Ernst surviving I got this:
It would certainly make for interesting times if Ernie does support Maximilian III more. A Habsburg Poland would be an interesting animal to say the least, however, I'm not sure if it would survive long-term.
I would like to add nuance, that with regards to the cost of defending his portion of Hungary-Croatia; the core of the issue apart from his brothers (I think they helped as Turkish raids definitely reached into the lands of the Styrian branch) were the estates themselves. I recall reading that even for Ferdinand I, convincing estates like Tyrol to contribute funds to assist for wars in Hungary was like pulling teeth.
Also mining rights in Tyrol at least had been mortgaged by Sigismund & Maximilian due to Sigismund's debts (Sigismund of empty pockets) to the Fuggers. I think the same ended up happening with the mines of upper Hungary but I'm less certain about that.