Generally? There's only ever been one SE model outside a slight capacity bump.
The SE shipped with a hybrid of the guts of a current at the time iPhone 6S (back camera, processor) and and iPhone 6 (Touch ID, front camera). I think it's a fair bet that if they do release another SE it'll have the processor / camera from the iPhone 8. and maybe the Touch ID from the iPhone 7 (i.e. non moving home button).
That said, I'm not convinced they will actually release another SE, at least not for a while if ever. Perhaps for the iPhone 9 they will have a new small form factor phone altogether. Calling the iPhone SE the SE indicates to me it's a special one off. I think they were caught off guard at how many ppl want a small / cheap iPhone, and so they decided to throw it together from the parts bin. When they released the SE even back then I reckon it was too late to add a small form factor iPhone 7/8.