I don't think Emily/Paget should come back. It would make it very awkward if she were to actually get back on the team.

Garcia, Morgan, Rossi and Reid are wounded by her 'death' and grief takes a long, painful time to heal. Having her return would only reopen old wounds, and inflict new ones.

Imagine how they would react if they knew Hotch and JJ kept the secret of Emily's wellbeing from them. They would see it as a betrayal. Having found out that Emily lied to them again would only serve to further fracture their relationship with her. She can't return, or the team would be broken by this devastating revelation.

Then again, would Emily's whereabouts forever remain a secret? Or would Ian Doyle return once more like Foyet? Would the writers ever entertain the idea that maybe one day the rest of the team finds out what actually happens without Prentiss coming back?

If she does return, it would be only to wrap up the Doyle situation. It would be unrealistic (at least for me) for her to get back on the team and then believe everything's normal again.

So is this Hotch's secret? It is saddening in the way he has to shoulder all this responsibility, this guilt and his team's grief. That he can't tell his team the truth.

On the issue of secrets, I feel that it is very likely the team is not going to take it well when they find out Reid's been keeping his headaches quiet from them. Would Reid's secret be resolved next episode (the title does seem to indicate...something - 'With Friends Like These'. Maybe he is finally compelled to tell them?) or at the end of the season?