I really want macro-based metaprogramming, like Crystal.
I also really want lightweight actor model for concurrency, like Crystal.
I'd like to have better performance, and to utilize the efforts behind LLVM, like Crystal.
I'd like to distribute my program at the object level across multiple or many machines. I've heard of dRuby, but I have never tried it, and at this point it'd be more effort to pick it up than it would to just use Celluloid's DCell or some such similar offering.
I'd like a higher level of modularity in what gets dragged along with my program. I don't want/need ObjectSpace, I don't want/need a bunch of extra classes that I never even called. When I build a release, only the classes that I utilize should be included. Java's Project Jigsaw does this.
I'd like to get rid of globals. I don't mean don't ship any globals, I mean NO GLOBALS, ever, at all, under any circumstance.
I agree that these should all be big breaking changes. Other people are writing their programs in other languages, and if Ruby is going to live onwards, we're not only going to have to capture new programmers but we're going to have to recapture old ones that have been scorned.
Frankly, I'm content to let Ruby die and let the Crystal crew keep moving forward. They've made tremendous progress and I foresee nothing but good things from them. On top of that, Crystal is already blazing fast, conceptually very easy to use, and seems to only be gaining steam on the development front. Documentation is a bit lacking for now, but I'm sure it'll pick up once the project gains more steam and especially once Crystal starts approaching some sort of 1.0.
I want to drop the mic with one last remark: Rails killed Ruby and I won't feel bad when Rails crashes and burns.