Well, if they port to .NET (CoreCLR), that will move them to the MS GC.
Yes, but it also puts them in an awkward situation! They recommend (or even require, for some platforms) using IL2CPP for release builds which will still use Boehm GC and not run as quick as CoreCLR.
Yes, but it also puts them in an awkward situation! They recommend (or even require, for some platforms) using IL2CPP for release builds which will still use Boehm GC and not run as quick as CoreCLR.