imo, It's pointless to keep waiting for a new technology that is non-existent yet. Get what you need only if you need it now. If you don't need it now, then save the money for rainy days...
Many times, it's the BBB bug influencing your decision. For the list of stuffs you want to shoot, I don't think 500D can't do those... If what you shoot requires high fps, high iso performance, better AF that it warrants the new spending on a camera body, then go ahead and buy it.
btw, "traveling light for better mobility", you should be looking at m4/3, EOS-M, or even NEX systems. The weight savings of those body + a superzoom is much more than a EOS-XXXD + 18-200.