However, I remember that because of the current BIOS (or firmware or whatever ...), they cannot be used in cMBP (or similar Macs that have exchangeable RAM bays), as to some message somewhere to find (sorry, can't remember where I read that, apart from that I did indeed read it).
I think you mean this link: http://forum.thinkpads.com/viewtopic.php?f=69&t=113461
To sum it up, the 8Gbit packages (which are necessary to build a 16Gbyte RAM module) are not currently supported by the Intel CPUs.
I guess the best option for me would be to sell it and save up for a Mac Pro 2014 Desktop.
Was afraid It would have to come to that. I really would rather upgrade my rMBP and pay the price
First of all, I have difficulty understanding why you need 32Gb of RAM (and why you even were looking for a laptop in the first place if you have such needs). Second, even if these new chips would work, an upgrade would be very cost prohibitive. The RAM modules alone are likely to cost over $200 each (and I am saying 'likely', because don't even appear to be in the stores yet), and an upgrade would be several hundred on top with a high risk of frying the entire machine.
If you absolutely need 32GB RAM, then your only options are one of the quite rare laptops with 4 RAM slots or a desktop. If you need a Mac, a 27" iMac is the most cost-effective option.