Maybe. But Spain will still be unable to do anything more than talking...
If he try to invade England, you can be sure who France and the German Protestant princes will use the opportunity for trying to get personal advantages (and maybe the Ottomans also)...
Karl has way too much enemies everywhere for conceding himself the luxury of a revenge for his cousins’ eventual death (who will be either for high treason - aka none of his business - or apparently natural)
I guess you're right. Although TBH, I think with Liz married off to a Protestant and Edward healthy, I wonder if he wouldn't try to marry Mary off abroad. If only to get a potential lightning-rod out of the country. Mary can't disobey her sovereign everyone AGREES is legitimate.
But I think we're digressing from the original point. If Liz marries Erik in 1549/1550, I'd imagine they'd be likely to have their first kid relatively quickly - two horny ginger teenagers