A perfect chess engine is one that always finds the best moves.
From a practical perspective we are getting close to that already. Statisticians have stated that they consider a rating of ~3600 to be perfect. Chess engines are approaching that level.
There are other ways to solve chess than just by brute force.
This is why I mentioned the possibility of a "perfect" chess engine. Of course, proving that the engine is perfect has its own challenges, but it may be a more practical way of "solving" chess.