I guess another way to do things isn't a bad idea, but if the main benefit of powershell vs. the "old" Linux way of doing things is that it works on objects then why not just move everything to JSON or XML instead of the plain text used now?
Config files will still be easily human readable/editable, current utilities only need to be updated to read/write whatever format is chosen and, perhaps, a new way of passing arguments to programs implemented (to save all the escaping/argument length issues - maybe some form of shared-memory mechanism). This way any shell can implement features to manipulate the objects since they're just formatted text to start with.
DTDs, or something for the same purpose, could be provided to easily validate the object text and ensure type-safety and such via a simple library which ensures everything is correct and is exposed in the scripting language of the shell.
It's all just serialisation with enforced rules, seems a much better solution all round than having to port all the .Net stuff.