I too was holding out for a hopeful last minute refresh.
However, at this point, it's not practical for me to wait any longer.
I need a new computer for a few projects by the beginning of October - it's looking like realistically, we're not gonna see the new iMac until the beginning of November, in terms of when you can physically have it.
At this point, it looks like a best case co-release with Mavericks, which we're all forecasting as a late October announce. I don't expect the wait gap/availability issues of last years iMac announcement [barring any drastic physical changes, which none of us are expecting either] - but I'd still give at least a safety lead time of 2 weeks from the announcement/release of new iMacs to when you can expect to have one in your home.
And then again, there's no guarantee new iMacs are released in October. Who knows, maybe they even "skip" a refresh cycle until something bigger and better is available to the iMac?
But me personally - I do believe that new iMacs will be announced sometime in Q4 this year. And despite that, I'm still looking to get a 2012 refurb in the next few days.
I do primarily audio work. For me, any new hope of upgrades still doesn't beat the deal of a current refurb.
Main point of interest being the processor for me - we're gonna see, realistically, a 5%
CPU increase overall with Haswell. Sure, there is AVX2 [which is leading people to believe that Handbrake is 2x faster on a Haswell], but unless things can specifically utilize the instruction set, it's going to be something that isn't a game changer.
Wifi - sure .ac would be nice, but it's not something that I'm not going to be able to take advantage of for another few years, at least.
PCIe SSD - yes it'd be awesome, and we can all hope for it, but a Fusion drive is going to do what I need for a while.
Graphics - not a concern for me - and the model I'm looking to get has a 680MX, which is already gonna be overkill for me [too bad you can't CTO refurbs...

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TB2 - probably the biggest thing to miss out on, if it makes it to the iMac this time around, for me. Purely for the expansion possibilities and bus speed possibilities. But again - not something that will prohibit me from doing what I need to do.
Now what I'm really waiting on - if Sonnet would go ahead already and get that damn Echo 15 out...