Bearing replacement canbe required for a number of reasons.
I would take an experienced machine guy and go look it over. If there is nothing broken, cracked or excessively worn that effects performance I would still consider it a good buy. Worn bearings are simply worn bearings and normally don't affect the shaft or the bearing hangers. If the replacement, a simple task, was done correctly the saw should be ready for another fifteen or twenty years of service. If the adjustments, fences, etc are sound, I would give it a go.
What you do today determines what you can do tomorrow.