I would expect Angel to turn into Angelus if Angel & Cordy meet that night at the beach when he was put into the box and in the ocean. Since Angel always wanted to be with Cordy and all. But alas, maybe that isn't perfect happiness.
I'm sad to see Angel go. I only started watching new Angel episodes this week, before that I was watching the re-runs on TNT. First episode I saw was when Wesley came into town in Season 1/Season 2 (I forget). But there has been talk of an Angel mini-series and/or movie on the WB in the future, so that sorta calms my nerves.
I always have the Box Sets though.