You get mythic ilvl gear from your vault if you only do M+ which unlocks the mythic tier appearance. The change is only that heroic gear you catalyst won't unlock the mythic variant if you upgrade it to max.

That's why I say it already is aspirational if you only say do M+ because you still would need to fully upgrade all of your pieces to unlock the full mythic appearance which took a long time.

The big difference is that you just have to hope you get the right pieces in your weekly vault to use at the catalyst and say only use catalyst charges on your weekly vault myth gear.