Just a recompile away, except this time, you don't have to deal with poor, proprietary, bespoke, low quality tooling, but you can instead use reputable industry standard tools like gcc, binutils, llvm.
RISC-V doesn't seem like the "strongest" ISA ecosystem, unless you mean among soft core CPUs?
I can't really see AMD/Xilinx or Intel/Altera offering a free 486SX soft core, even though they legally could. It would I expect use a lot more LUTs, and be slower.
Licensing Cortex-M1 doesn't seem likely either.
Note that RISC-V hard cores in FPGAs are already a reality, including Microsemi PolarFire as well as GOWIN GW2N.
Not long from now, I expect every FPGA vendor to switch over. The ones that already offer soft cores won't take long.
>RISC-V doesn't seem like the "strongest" ISA ecosystem
RISC-V is rapidly building the strongest ecosystem.
It already is the strongest besides x86 and ARM, and the position of these two isn't, by any means, secure.