I guess the bottom line would be a multi-tool (i,e, Leatherman, Gerber, Victorinox, SOG, etc).
However, if I was just downsizing, unless I lived in a condo with a maintenance man, I would hold on to my basic hand tools (Hammer, chisels, a couple saws, screwdrivers, etc). as well as a couple battery powered drill drivers. As for power tools, my table saw would be the last to go. Even if I couldn't physically fix what needed fixin', I could coach someone else through the process. (That last thought would also apply to garden tools, wrenches, etc).
Might look at it differently if I was rich. LOL