The small block is a core characteristic of the Corvette. However, that has been because it is always the best solution for what needs to be done. Recall the C4 ZR-1 used a bespoke LT5 because they couldn't do what they needed to do with pushrods. It shouldn't seem like they are arbitrarily choosing the small block. They do so for a reason. Same reason that they would choose something else in the future, if necessary. Do I want to see a shift away from the small block in Corvette? Not at all. One may be concerned that even if the "C8" uses a special engine, that it will trickle down and replace the rest of the line over time. But that didn't happen with the LT5 because, again, they got what they needed from the small block. Don't forget it provides key advantages, not just sheer legacy. So you'd have to credit its replacement (if any) with those same things if it has even more advantages.You do realize Zora Arkus Duntov, the man who made Corvette what it is today, originally wanted Corvettes to be rear mid-engined right? As long as the small block V8 doesn't go away no one will care where the engine is.
One thing I'd be careful about if I were chief engineer at GM powertrain is to make sure I didn't lose the tremendous developmental advantage of leveraging engine R&D from Corvette all the way down the line.