The 180mm macro design speaks for itself, and I think the 65mm macro design is for a direct replacement for the MP-E. Knock on wood, haven't bought either lens yet. I'd wished they would have increased the 180 macro's aperture a bit but the new design will probably be worth it regardless. Lots of interesting patents from Canon lately - if refreshes are your thing.
180mm: Good for you guys and the guy that sold me his 3 days ago...
Well, there's a good reason I shouldn't have written that.
First, you knew what you were doing when you bought the lens, so go use it and don't worry.
If you still are worried, why? The price of the new (and unannounced) lens won't start impacting that of the old lens for some time. Few enough people probably even know of these patents and it will take a long time (Canon or Nikon doesn't matter here) for it to roll out, even if they announced it today.
I haven't followed pricing trends before a replacement launch strongly but my belief is that lens prices of a previous version should dip most right before and right after the launch, and then stabilize after. If you're so worried about the price of the purchase (which I don't think will dip enough to really make it a "worthless" buy) then you perhaps couldn't afford it in the first place.
Your best chance for a belly laugh is to go out and make pictures that I can't since I don't have a macro lens. And even if I do get a newer version macro, it'll be more expensive and you'll still have some lead time with better pictures out now.
My final thought is this - if you go out right now and buy a camera body, how long will it take until that camera's value is reduced appreciably? Even camera bodies, which are
arguably obsoleted by newer models (depending on who you ask of course) do retain some of their value, but people buy them regardless. If this were a camera body I would be more careful with my words since a lot of people's feelings get hurt about new camera bodies, but with a lens that's to be replaced by a lens that will be more expensive (partly due to inflation adjustment, partly just the cost of running newer equipment to manufacture it) I don't see the worry.
Anyway, go out there and take some pictures without worrying. You needed it, bought it, and nothing is preventing you from being happy with the investment aspect of it either. For all we know the current version will become regarded as a "classic" and people will still demand it later on.