To quote O Brother where Art Thou: "Do not seek the treasure! It's bushwhacked!"
I really hope it works out as it seems like you're a 99.9% yes on this offer, but I think you could be really cruising for a bruising.
So you've got a rural hospital where 5! docs are all set to 'retire' all in the same time window (that almost sounds like an entire practice). They're trying to rope you in with a 4 year commitment with devastating financial penalty if you don't live up to your end of the bargain. It took them 3 1/2 years to hire the last doc so when all 5! docs leave and stick you with their patients (rural 'older medicine' often times means quite a few patients on benzos and narcotics) and you're seeing 30+ patients a day for essentially nothing because the majority are government insurance. If you speak to any of the 'retiring' docs, expect for them all to speak glowingly about staff, patients and working for the org in general. I would never sign anything longer than a 2 year commitment under such a circumstance but they'll probably never go for it.
If this offer were for anywhere but your hometown, you would probably never give it a second thought. We can usually be happy in a few locations, but can easily find misery anywhere. Really think long and hard about this one.