This could be a way to introduce Carol Danvers as a Shield agent. This is must likely going to bridge together phase one with phase two. "How I Met Your Mother" was renewed by CBS last year for another three seasons but that does not mean Cobie can not appear in this if scheduling allows for it. She wouldn't be a major character, but Maria Hill could make occasional guest spots in it.
Not to mention we've yet to see Sharon Carter. Or Jessica Drew (although she could be hung up as a Sony property given her name). Like I said before, the character possibilities and with Joss involved are nearly limitless.