I have been fishing Cumberland regularly and year-round for the past 8-9 years and haven't noticed any appreciable decline in largemouth numbers. I was one of the camera boat drivers for the FLW tournament there. I followed Clark Wendlandt around on the final day. They didn't need me the day before, so my partner and I went fishing for about 4 hours. I caught 2 LMs over three pounds and another over five, all on a buzzbait. At least on that day and in the creek where we were, there was no shortage of largemouth.
In the same area two years ago, in January and February, I absolutely wore out the largemouth with a jerkbait. We went so far as to have one of our favorite tackle shops order some for us because we couldn't find them. I have noticed a decrease in the number of spots that we have been catching, but that is probably attributable to our evolving techniques. We don't fish cranks as much as we used to, me in particular.
As far as the issue of whether or not stripers eat largemouth, I only have one experience to remark on. On New Year's Day a couple years ago, I had just caught a 4 pound LM on a Rapala crank. My partner wanted to cut across the creek to fish some laydowns. I started trolling across the creek and decided to toss my crankbait into a school of shad that was out in the channel. As soon as that crank got down to its maximum depth, a 12 pound striper nailed it. We were laughing our butts off because I had it on an old glass rod and was using 12 pound test. When I cleaned that fish, it had 19 shad and about a 9-10 inch largemouth in its belly. That proved to me that at least some stripers will eat largemouth.