Kongzilla will never happen.
The Rhedosaurus COULD happen for a number of reasons:
1. It's an OLD US property - acquiring the rights would prob. be easy/inexpensive.
2. A LOT of people would buy it, in the US AND Japan!
3. 'King Kong' was the original seed of the idea for Godzilla, way back when. But 'Beast from 20,000 Fathoms' was released the year prior to 'Godzilla', & is acknowledged as the direct inspiration for Big G's look, by Tsuburaya & others who worked on the film. The historical connection between Big G & Rhedosaurus is undeniable, & I'm sure Bandai is aware of this.
So, never say never - except for Kongzilla, using 'never' is prob. safe there.