Once a rotary starts to smoke how long will it last?

Here is the deal. I looked at an '86 that has been sitting for about 2 years. It was starting to smoke when they parked it. I started it and smoke filled the neighborhood but died down after awhile to hardly noticable (but still there). It is pretty beat up but it was only $500.

Might be a good to drive in the winter instead of my good car.

How long will it last?

 

Is it white smoke (coolant) or black smoke? My 91 N/A started blowing white smoke at the end of winter.. I chalked it up to "it's just cold outside." HA! It just got worse and worse.. eventually, it became such a smokescreen that it would last for 5 minutes, and was completely embarrasing to fire up.. 2 months later, it was just rediculous.

 

It is black. I expect it is the side seals are leaking.

I am curious as to how long will it drive that way? Will it just start smoking so bad I won't dare drive it? Or will it just croak?

I could always do something to it in the future but would like it to make one winter