There are around 20 outstations in the US that have UCs and a handful outside the US. Aside from NRT, would there be connecting traffic at any of them? 4Y and WK could use a *A lounge here as well.
Interesting to know, I wasn't sure how large that space was. Where gate A1 is would be pretty sweet and there are already bathrooms down there plus escalators. Where would 3M go though? I'm not sure if there any other gates at ground level.
It would actually be a level up, above the concourse (elevator through the double doors).
One consideration for lounge location is to drive partner visits, which can be a nice revenue stream. Unfortunately for TPA, the other *A carriers are in different airsides (AC in E, others in F), all of which are behind different security checkpoints. It's an inefficiency of the TPA landside/airside design, with security in each satellite. I am surprised that after all these years, AC never co-located with UA in A. Their operation isn't huge and could be absorbed in common-use A gates, if not within the United-exclusive leasehold.