This is an excellent point to consider. Perhaps this is why it may be a really good idea to just get the highest spec MBP they put out now, while just getting the minimal HDD and RAM since those 2 can be continually be upgraded.
*** As an update on how my 2012 MBP is doing (if anyone cares at this point) I have easily 90 hours of active use on this machine since I got it last week (not counting the 2 nights I let it run over night to encode some batches of video in Compressor). I would break down my usage since getting this last Tuesday like this: 75% video editing/encoding - 15% Web browsing/web based work - 5% Photoshop - 4% MS Office applications - 1% General goofing around.
Summation: This machine ate through anything I threw at this machine. The upgrade to the 750 Momentus XT that has 8GB of SSD has performed flawlessly, no beach ball, no studder, no lag, just zippy performance that was better than the 512 Momentus XT that has 4GB of SSD that was in my previous 2011 MBP. The 16GB of Corsair Vengeance RAM that I put in has worked like a charm and has not produced any beach balls or any issues to speak off. I did run this new MBP for a day with just the stock 8GB and then after I put in the 16GB I noticed a smother, faster performance for how I use a machine over the 8GB stock RAM. A note about the OS, I stuck with Snow Leopard on my 2011 MBP, and since this 2012 came with Lion, instead of staying behind, I choose to move forward and for everything I ask of this 2012, the OS Lion has not been a noticeable factor in holding me back from anything and everything runs well.
There you have it, that is my experience. Hope this has helped many of you out there in the choices you make or don't make on the classic version of the MBP.