Powershell will probably be fine. Besides them both being a REPL and scripting language they're very different. I guess the simplest way to put it is in powershell you're passing around objects and in bash you're passing around strings. That's an oversimplification though. I'd start wondering about powershell's future when bash starts getting the ability to tap into .Net the way powershell does.
As exemplified by this announcement, Bash in isolation is not that valuable. It's the standard UNIX tools that most Bash scripts just assume are there that really round it out as a platform. Supporting the piping of objects instead of text? Not such a big deal. Replacing UNIX tools with object versions? I agree - very valuable, but now a massive undertaking involving redefining a lot of flags, etc.