They're definitely not going to trade Hoerner now. My thought was he could be used to acquire a front line starter if they had Bregman at 3rd and if they thought Shaw was ready at 2nd. Shaw has played some 2nd in the minors. Not sure I'd use Hoerner for Cease anyway, though, since Cease only has a year left. Hypothetically, that'd probably be a 1 for 1 deal, with maybe a couple low minors guys going to the Cubs.
Not sure what the Padres want, and I don't think I've seen any rumored Cease deals. They're built to win now, so I'd assume they'd look to upgrade at 2B/LF/DH with major league talent, and maybe grab some lower level lotto tickets to develop, which they seem to be very good at.