A couple thoughts:

The 970 will cost less now, but the 990 will likely have a better resale value when you replace it with the 997. From that standpoint, spending a little more now may save you a bit later. At worst, you'd break even and have the better unit during the interim. Plus the 990 and 997 are roughly the same size, so your equipment rack will already be situated to accommodate the 997.

The $200 discount for 970 and 990 owners who want to buy a 997 is good for six months after the 997 is released. Rumors are putting the Sherwood R-972 in production possibly as soon as late April, so the earliest I anticipate the 997 arriving is the front end of July. If you think you'll buy the 997 before the year is out, you would still have that discount well in hand.

The Klipsch speakers you have are going to be pretty efficient. The RF-35 has a rated efficiency of 98dB - a speaker like that shouldn't ever need more power than the 7125 can offer, so with those speakers in mind I would have a hard time pushing you to step up to the 7500 or a stack of M2200's.