posible SSD becomes standard as well as new design.4K might have to wait for 2015
There definitely won't be a case redesign. That was just done in Fall 2012 and the screen lamination process was so complex they couldn't even ship the 27" in any large numbers until March 2013! Typical case redesign cycle for the iMac is 3 years so that would likely come late 2015 - probably with a 4K option. That's still a long time from now.
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and i don't think the first generation of 4K iMac will be flawless
Exactly. Same issue with the first gen Retina MBP's. The Rev B version of a 4K iMac will be the one to get, but now we're talking 2015-2016. If the OP wants an iMac, buy now and enjoy. It's an awesome machine as it currently stands.