Once upon a time, FF was unknown in the US (pretty much previous to VII... yes, hardcore NES guys knew it but not the general public). The same applies to MGS for the PS1. While I doubt Trusty Bell or Mass Effect will move many units in the US, I think Blue Dragon and Lost Oddyssey in particular will move quite a few consoles. At one time or another, every franchise was unknown. And the pedigree behind BD and LO are huge. And you know that MS will advertise the crap out of them (LO in particular, I think).
On the PS1, MGS was one of three big franchises that moved consoles. The other two were FF and GT. All were released in a small amount of time. I hadn't played a PS before going to a friend's house and playing GT and MGS. I ended up with a console the next day. While MGS by itself may not be an enormous system mover in Europe and Japan, I think it would move a healthy amount of consoles in the US. I may be wrong, but that's how I feel about the franchise.
Well, you can take that up with people who played Final Fantasy on the NES, people who played Final Fantasy III on the SNES, and just about all of Japan where 1-6 were released. The same with people who played Metal Gear on the NES and the MSX2. However, almost everyone will tell you that the predecessor (FF, MGS) were outsold by their respective sequels. You can also compare Mega Man sales with Mega Man II.
The main point is that these were credited and established titles by the time they made their way to the PSX. Yeah, Final Fantasy VII and Metal Gear Solid moved consoles (Not sure of the latter) but this wasn't their first foray into the gaming world.
That's why I'm basing my assumption that Mass Effect, Lost Odyssey and the others will not move hardware, and the fact that Blue Dragon really didn't make a dent in Japan (That was supposed to move a lot of hardware, wasn't it?)