After 449K miles, is this how my '80 245 DL ends?

Driving into school this morning, I started getting some sort of mist/steam that came through the vents, and through the windshield defroster vents. Temp set to full Cold (as far to the left as it will go).

This "mist" left some particularly nasty "fog" on the inside of the window. It leaves a "foggy" residue on the window (which oddly enough did a good job of removing some adhesive that was stuck on the glass from a parking sticker.) It would not just "melt away" like it usually would (I had the window down full).

I tried turning the heater control knob to hot and warm settings, but it didn't seem to make much of a difference. Maybe the hotter settings made more fog in the car, but I was trying to pay attention to the road which was somewhat difficult.

Once I jumped on the freeway, that's when the fog started pouring out of the vents.

What should I do?

If this is the heater core, it may be the final nail in the coffin of my beloved wagon. As it is right now, the steering column is shot. A fender needs replacing. The electrical system is still being funky and I can't figure out why. Problems seem to be adding up, and time is something I really can't spare these days (main reason I don't frequent this forum as much as I use to.)

I've done the heater fan in this car, but as far as I can tell, doing the heater core is a lot bigger of a task.

Is there anything else this could be?

Thanks as always.