Playing G at PG is a bandaid that (IMO) JB will use only as long as he has to (while KJ comes up to speed). Moving G away from the 3 creates a giant hole at the position (there's no experienced/capable backup there). If it's necessary, I'm intrigued by your "option 3", for a couple reasons:
1. With G at PG (and a hole at the 3), I don't think JB is going to turn to a 6'6 freshman guard (MR). Richardson could play there in a small lineup, but to me he projects as a volume scorer up top, lacking both the length and defensive experience to tackle rebounding and defending the SF position against 6-7/6-8 players;
2. I also don't see Roberson sliding over to the 3. While his size fits the spot, his (present) skill set does not. So playing Tyler Lydon there is alluring because he can shoot it from outside (we need outside firepower to take the heat off TC). If Lydon plays, I can actually see him at the 4 on defense and the 3 on offense. Having 6'9 200+ (Lydon) on the other side of the rim (opposite the center) frees up Roberson to rebound/get put backs in space around the rim rather than trying to bear-wrestle 240 pound guys for position.
This year is going to be a hybrid year, with lots of switching to take advantage of matchups, skill sets, experience, the hot hand, etc. I do think KJ has the talent to be a great player for us .. WHEN he gets there is obviously a question. Having a swiss army knife like G is a luxury while KJ is learning, with G's scoring ability, his length and his experience. What I'm not sanguine about is his ability to stay in front of ACC guards ... we were getting penetrated at will by some teams, leading to easy baskets or dishes/dunks (KJ was no better on D). For this reason, I don't see G as a panacea at PG, nor do I see Richardson getting a ton of minutes if he plays ole' defense.