Thanks for your answers.So, you dislike small sensor, 18MP is too much for you, 8fps is to slow and you hate 7D for having all of those "features". Do you hate your 450D even more? It looks like you want that 1D3 badly and you are asking us to help you to justify the purchase . If it will make you happy then just go for it. That's all that matters, really.
I'll just answer some questions you wrote.
I do want to do wildlife (probably most of it will be birding - I love birds!) - but at the moment I'm mostly doing landscape and portrait. So what I'm wondering is if I get me a 1D Mark III for 1500-1600$ now - wouldn't it be great paired with the new 5D Mark III (to come) or a used 1Ds Mark III (to be outdated since 1Ds Mark IV by then) ?
That's what I'm wondering. I'm fully aware that the 1D Mark III isn't a FF camera - since it wouldn't be for shooting landscape and portraits, at least not after I have a full frame camera - I would want to use it for faster things. Maybe I could even end up with buying a 5D Mark II and a 1D Mark III?
Since they're both awesome cameras on their terrain - and paired on pretty much any terrain.
Another thing: I strongly dislike the 7D. I just hate it. Everyone, even those that clearly do not need it, buys himself/herself a 7D. Yet I also dislike the small sensor with 18 Megapixel - why do I need those darn 18 Megapixels? I don't. As for the 8FPS - they're nice, but compared to 10FPS - no more that nice. Even less nice if you take a look at the release years of those two compared cameras. ;o)
However: what do you think?
Most probably, 5D3 will have more than 20MP and less than 8fps, so you may hate it as well.