1. New Intel processors
2. NVidia GPU with top specs
3. 512 SSD as standard
4. 16 GB RAM (>1600MHz) as standard
5. Better heat management
6. Space grey (hey why not?
)
7. Significant improvements in OSX (not silly stuff please) and ironing of bugs.
While I like your list, here are my thoughts on it, just for the fun of it.
1. It would be Broadwell, which would make the computer slightly faster. The CPUs on current riMacs are already super-fast. But every little helps.
2. Most likely not going to happen.
3. Definitely not going to happen. Maybe in, like, two years.
4. 16Gb seems a possibility. >1600Mhz might happen as a consequence of the new MB/CPU, but wouldn't make any difference in performance, really.
5. Knowing Apple, they would probably use lower TDP of components to shrink the casing even more, so probably not
But seriously, if there is better heat management, it would be because of new Intel/AMD/Nvidia components, not because Apple had anything to do with it. Besides, the base Retina iMac is really cool (way cooler than my 2011. iMac). I know the top of the line Retina is warmer, but I'm just saying the heat management is not bad in this generation either. It's only bad if you read the 10000000-post-long topics about throttling on these forums
6. Only if they do a major visual redesign. And who knows when and if this is coming. I think they'll keep this look for at least one more year. They usually find a reason to redesign, like, the ability to make things smaller. Not sure if this is coming anytime soon - but who knows.
7. I agree, and I would REALLY like this to happen. This is the first time I don't want dramatic new features but performance optimisations instead. Apple, find a way for my base model not to lag in Mission Control!
And fix the bugs
Who knows - maybe something like this is coming. Supposedly iOS9 will be a bug/performance version so it may happen with OSX as well.