While LEON isn't going away any time soon (especially given the recent release of the new LEON-5), I very much get the impression that the long-term plan is to replace it with RISC-V based solutions such as NOEL-V. Nobody can throw out working systems, but if you are starting something brand new, does it really make sense to base it on an ISA which the rest of the industry has essentially abandoned? Even its originator (or successor thereto) has basically walked away from it. Aerospace stuff is as expensive enough as it is already, getting stuck on a niche legacy ISA seems like a recipe to only make it even more expensive.
If you look at the page for the gr765 the parent poster linked to, you can see that the customer can choose the gr765 with either SPARC or RISC-V cores. I think you're right that the plan is to transition to RISC-V, given that the SPARC ecosystem otherwise is pretty moribund.
While LEON isn't going away any time soon (especially given the recent release of the new LEON-5), I very much get the impression that the long-term plan is to replace it with RISC-V based solutions such as NOEL-V. Nobody can throw out working systems, but if you are starting something brand new, does it really make sense to base it on an ISA which the rest of the industry has essentially abandoned? Even its originator (or successor thereto) has basically walked away from it. Aerospace stuff is as expensive enough as it is already, getting stuck on a niche legacy ISA seems like a recipe to only make it even more expensive.