I know absolutely nothing about this thread but I suppose that Arthur wouldn't die as young (they'd make sure he would be kept safe at least until he had a male heir). He would probably still marry Catherine as the Spanish would gain even greater influence over England (with the death of Arthur's parents). If that's not the cause of the marriage, the interests of the regents would be (as they are likely to gain from an alliance with Spain against France).
Arthur is definitely going to live here, him catching the sweat was mostly because of some bad luck. Catherine marrying Arthur is put in question. In otl Warbeck and Warwick were killed due to the threat they posed to Arthur and hence their daughter. Not sure if the Catholic Monarchs would accept that risk here.
I can definitely see Edward Plantagent and others being blamed for the fire (with propaganda they could use the fire as an excuse for treason and get rid of them and rivals for the throne).
100%, they’ll say it’s a part of a conspiracy and executions will happen very soon, probably as soon as they forge fake letters and more.
I'm not sure about Arthur's regency, but I suspect Margaret Beaufort would be included (as she was his grandmother and arguably the one who made the Tudor dynasty possible).
I am currently thinking it will involve his Godfathers, the Earls of Derby, Oxford and Arundel and his Uncles via blood and marriage, the Marquess of Dorset and the Earls of Devon, Surrey and others. Margaret Beaufort will probably also play a role since Derby was her husband.
His reign would probably last from 1497 - 1551 thereby dying at the age of 65 and having reigned for 54 years (most of the Tudors died at an old age for their time).
Him leaving to 65 is a bit of a stretch IMO. Maybe he dies in 1549?
Religion wise - England would probably remain Catholic (at least for another century).
It probably does stay Catholic since Arthur will probably get a son out.
Economy wise - it would probably be bette as Arthur wasn't interested in wars and an alliance with Spain would be an economic advantage (at least for Arthur's reign).
Arthur was taught how to rule and administer a Kingdom so he’s so well economically speaking.
Succession - if they still marry in 1501 and have children then there won't be a succession crisis like under Henry 8th in OTL.
If Arthur and Catherine to marry in 1501 and have children the succession is perfectly safe.
That's all I have to say (regarding the fact that I have no knowledge about this thread but a huge passion for the Tudors)
No problem. I also have a passion for the Tudors.