What is likely to happen if I leave my athlete’s foot untreated?

It could . Spread, it could cause toenail fungus, it could potentially enter thru cracks in your skin and cause a cellulitis.... Why not treat it?
It may stay around . Untreated athlete's foot sometimes gets better, but more often it persists- stays there for a vary long time and can get worse.

Related Questions

Is it true that sporonox 200 is bad news for my liver? I got athletes foot that wont go away and my Dr. In S.A. Prescribed it?

Sporonax. This is an anti-fungal. All anti fungals do result in some form of liver issue. Most of the time its tolerated well. Fatal issues can occur sometimes. I assume you tried topical antifungals first. Read more...