Honestly I think it depends on what the magnates want, if Lajos/Louis II had a male heir he'd still have to be elected as King and might lose (precedent for this is Albert II of Habsburg (HRE, King of Hungary & Bohemia too) whose son Ladislaus the Posthumous was passed over in Hungary for a Jagiellon because they felt he could better defend their interests and help Hungary fight off the Ottomans. It might turn into who curries the most favour amongst the magnates.
Now assuming Lajos/Louis II heir is elected, the next fight/struggle would be over who would get to be regent. His mother Elisabeth may claim regency but most women never succeeded in being regent of Hungary as the nobility were usually against it, Ferdinand can claim regency on behalf of his nephew and sister but that didn't work when Frederiech III tried it for Ladislaus Posthumous or the magnates may try to force Elisabeth to marry one of them so he can be regent. Either way the magnates will most likely guard jealously their position, privileges and power within the country and try and make the King have a weak/puppet like position.