Probably my biggest fear with the V20 is that it will be a total departure from the V10 instead of improving on it. There's a lot to like about the V10 but it had a few glaring flaws, like the battery life and speaker. I would have been more than happy if they just took the V10 as is and improved upon it instead of re-designing the phone from the ground up, which is what it appears they're doing with the V20 based off the renders.
As far as button placement goes, if the volume buttons are indeed moved back to the side of the phone then I personally won't have an issue with this. Yeah, I would prefer they kept it like the G3, G4 and the V10 because I like the sides of the phone clean but I've gotten used to the volume rocker on the side with the S7 Edge, so this wouldn't be a deal breaker for me. I think the things that would keep me from buying the V20 would be overall build quality...if it's not as durable as the V10, modular design like the G5, lack of expandable memory, replaceable battery or IR blaster. Pretty much if the phone is just a larger version of the G5 then not interested. I'd go back to the V10 before I'd consider the V20 if that happens.