For me, 4E still has lots of life left in it. I've got another eight or so campaigns I want to run and will endeavour to do so in the years I have left.
That said, I look longingly and lovingly at 13th Age and expect I will be running that before the year is out once I have the new 13th Age Bestiary and 13 True Ways, but 4E will still be my preferred ruleset. The fact that I am looking at 13th Age as well shows I do have an appetite for something different but, for me (IMO/YMMV), what I have seen from Next is not so much a new edition of D&D but a new edition of AD&D and that's something I am definitely not interested in going back to.