Price wise, there is place for a GS, the price gap from a ES to a LS, a top spec ES isn't much more than half a "base" (if we can call it a base spec given how much they have), is quite huge price difference, but when there are so much more SUV buyers... Don't know is it were going to be a good financial decision... Even being a high quality and beautiful looking Mirai-like GS... Specially when there is going to be a new NX and a new flagship SUV...
About the ES, I find it really hard to say it's similar to a Camry... They have the same platform, but last year in a small car show I got the opportunity to get into a Camry and 1min after into a ES... Besides similar overall dimension, a Camry is nothing like a ES in my opinion... Even ES closing door sound is miles apart from a Camry... For the non-enthusiast buyer they will never say it's similar or almost the same thing.
In my opinion, ES is a beautiful, well built and priced car that can replace a GS for the majority of buyers.
If I would love to see a new GS F? Sure! But I don't see it as a profitable program... I think SUV's killed the GS, no one else...