Paxton lost just 1% to Cornyn. If he gets Hunt’s votes, he

will beat Cornyn in the runoff. So I don't think Paxton will drop out. If he did bow out, probably Trump offers him a cabinet level position like DHS to replace hated Noem. But again the position only lasts two years. We shall see what happens. 
Another thing, if Cornyn wins the nomination,  many MAGA will stay home in November.