What if Alpha Zero already “solved” it. If not then Alpha one or Alpha two. When it plays the way it wants it never came close to losing a single game VS Stockfish, right? So, it’s not “solved” in a technical sense where all moves are known to a machine, but rather solved in a practical sense maybe?
When you drive somewhere you don’t know all streets and surrounding areas, and don’t have to, all you have to know is specifically YOUR line that you travel. So when Alpha Zero picks a line and it says: “Based on my previous 4 millions practice games White’s winning chances are 80% in such a position” that’s fairly close to saying this line has been solved. I mean when NY Times meter thingy said Trump’s chances of winning are now 80% Liberals were having a meltdown :) Even at 70% it was already clear as day who will win. In fact once the meter starts to rapidly shift from 50/50 to 60% winning chances for one side and growing with each passing minute, you KNOW where this is going and which side will win.