I could see it being the SC again.
That said, if it's a halfway split between the LC and the RC, it's gonna be another generational model downgrade.
It can't be a CLE hatchjob that gives you a C Coupe at E Coupe prices.
This thing needs to be nicer than the LC or it's a flop.
I think there is a world where this new coupe could be different from the 1RC and LC instead of having to necessarily be nicer than the LC. RC has been the entry level "IS coupe" of sorts, and both IS and RC are very old now... LC is very much a GT coupe. There's a lot of room in between those two classes for a new coupe to be successful, and trying to cover more ground with one model probably makes a better business case than two of them as we have now. They could do everything from a luxury trim to be more like LC, to a full blown F focused on performance.
The biggest changes I would expect are weight reduction and new powertrains, which would both create significant differences with RC and LC. If this revised GA-L platform has the car weighing 3,800- 4,000 lbs and they pair it with a 400hp turbocharged 4cyl, or say a ~450-500hp turbocharged hybrid powertrain, that will be a very different coupe for Lexus. Much more modern and probably more performance oriented as well.