I agree with your take.

I was never a Trekkie, but my gf has been since she was a kid, so she's been sharing the setting with me.

I really, really liked the borg threat, but the Queen cheapens it for me significantly. Not so much that she exists, but that she's literally the Nexus of the whole thing.

My suspicion/prediction was that the borg would be undone by some sort of biotechnical exploit, likely either some sort of "virus" that would be assimilated and spread through the system, nullifying/destroying them or their abilities...or some kind of trojan horse, similar to the virus but something that would take federation and romulan cooperation to build something that was very desirable to the collective but with a built in vulnerability that would leave them open to a specific attack (maybe something like capturing a Borg and altering them in a way that used the Borg "learning" against them, by countering the advantages of things they assimilate and then learning at the same pace as the Borg, but in learning how to halt their progress)...or maybe some sort of star trek version of a DDOS where they were able to somehow overwhelm the Borg with things to assimilate, but that were "dumb machinery"...with a huge glut of these assimilations of mundane subjects, maybe it'd have the effect of reducing the average of the collective, making it more beatable. Basically adding lots of dead weight to "bring down the curve".

Or, of course, there was always the possibility of time warp or Q related nonsense, but IMHO that would have been even worse than what we got with the Queen. As popular as Q is, I never liked that addition to the setting.