I had been planning to buy a new laptop to replace my MBA. I tend to use my laptop for writing and other basic stuff, so I generally get 7-8 years out of them. Given that the last transition was supported for about 5 years, I see no reason to buy one now until the ARM models come out. Whatever I buy today will be a Windows machine within five years, and I don't need one of those.
If I had just purchased a Mac Pro, I'd probably be annoyed, but in general those are used by professionals who likely depreciate them and write them off within five years anyway, so maybe it wouldn't matter. I'm a little sorry I bought a Mini last year, but I guess if I get six years out of it it'll be okay. If Apple cuts off support for Intel chips in three, that'll suck, because I run Logic on the Mini.