I could definitely buy into that storyline, but I have a secret terror that Natasha is going to show up as a SHIELD agent "to protect Tony" or some BS and then proceed to be A Designated Love Interest until they forget about her and get back to blowing things up.

Oh, you know Tony has to be in the equation, even if it's only by finding the security tapes later and putting them into his collection. :D But the porn totally isn't gratuitous. Natasha is distracting her so she can leave an exhausted but cheerful Pepper in Tony's office and then slip off with the Technological Doohickey Of the Week. It's a tried and true technique. She probably didn't count on the fact that Pepper works for Tony, and is too smart to be duped that way. There may be handcuffs involved.

"Why do you have these in Stark's desk?"
"It's Tony. Don't ask."

I like Steve randomly being defrosted. They need to get moving on that, chop chop. They haven't even cast him yet!