"If I were to consider..." Means you're not, at least for a while.
In this case, I would replace all 4. If I were to be driving it, that is.
It's a problem for you now, so fix it.
If you were to try and sell it with those bad tires, anyone who cares enough to look will offer less.
As in: if I must buy new tires right after I buy the car - I'm not paying your asking price.
Get a rep for selling junk and it will stay with you - another thing to avoid.
Also recently bought a slightly used truck. An insisted on part of the negotiation - replace the rear tires with new to match the front.
A tire that barely passes tread depth is dangerous in winter.