"Will contributions to Akka that use ASCII arrows now be rejected?"

I guess that this will be solved and has been solved in that commit with a formatting tool, but for me the answer to your last question is definitely "no", putting unicode arrow "aliases" in the language is a completely useless cosmetic feature.

How many programmer will type a unicode arrow manually? Is this really necessary? I'm generally against adding purely cosmetic feature like this one, if it does not improve the language in a clear and tangible way, just leave it out.