I dont think its that important unless you plan on getting $5000 tv in the next 7 years. If you plan on doing so then you can get a lesser model thats new like the A820 which does support 4k and it would probably be near the same price unless you are getting some kind of great deal on the 1010.
The reveiver I got today was bought for about 7 years ago and the only reson to switch is the HDMI switch, it will make life alot easier. So that makes its vary important that the new unit will be a future proof as possible so I don't need to buy a new in a couple of years again.
So, will the A1010 be able to forward 4K resolution or will I have to use a A1020 for this? I supose that the upscaling will be done in the TV It just dont feeld right to let a reveiver do this part.
Not important, in my opinion. Any difference in 4k is going to be minimal anyway. Unless you have a 100"+ 4k capable TV. And even then, the difference will probably be negligible.
I think those with very large screens would disagree with you. For me and my 50" plasma I do agree the difference would probably be negligible. There are incremental improvements in the 4520 apart from 4k that do add up to make it a better pre-pro/receiver than the 4311 IMHO. The 4311 probably has better amps than the 4520, something has been sacrificed to make it weigh less but this doesn't matter to me as I use it as a pre-pro. Its also less expensive than the Marantz equivalent pre-pro and that is what I think it should be compared with.