2 observations as someone who owns 4:
1) SSDs, though very fast (and some models, like OCZ and Intel, with firmware updates fixing most speed problem) are built for use durability and, on paper, longevity. The longevity remains to be seen, but the main point is no moving parts and solid performance. Do your homework; many SSDs currently available on the market aren't much faster than their MUCH larger counterparts (especially 1TB-2TB platter drives); again I point to OCZ for speed and Intel for reliability.
2) SATA III is just beginning to enter the mainstream. As such, NewEgg only stocks 2 SATA III SSD drives. I expect that SIII will overtake SII in the next 6-12 months, at which point SII SSD drives may drop in price as they become discontinued. Possibly not considering how many SII systems are out there, but since SSDs are a high-end item at the moment, and high-end buyers will definitely migrate to SIII...
Just my 2 cents. Also note that, in most cases, you only really need 64gb or 128gb (I am typing this on a hackintosh notebook with a 64gb drive in it). An external case with a cheap, much larger drive, especially via eSata or USB, will work fine for non-active files. All of this depends of course on what you do with your computer, but I am quite content with the performance of my drives (64gb Kingston V in my netbook [on the slower end but much faster than the stock drive and WAYYYY more reliable], 32gb Patriot S-100 in my server [all I need, boot OS and linking my drives to the network, wicked fast after the firmware update], and 2 32gb OCZ turbos in my G5 striped, INSANELY fast, used for graphic design and audio/video editing). I plan on picking up two more 32gb OCZt drives when I upgrade to a 2010 Mac Pro, whenever they come out.
So my shpiel aside, the answers to your questions:
SIgnificantly decrease? No. Even the next gen of intels won't drop them much, and with SSDs you get what you pay for, so be wary of things TOO cheap.
As for waiting to purchase a macbook pro, no. Buy it if you need it, it will be much cheaper (and you'll end up with a much higher end drive) if you buy it now and swap in an SSD when you can afford it. Apple's SSDs are decent but by no means on the high end.
I don't think SSDs will ever be, gig per $, on par with platter drives. I just don't see it happening; by the time they near it platter will be obsolete and replaced by holographic (or some other step up, holographic is just the most recent I've read about).