Story-wise I’m not sure there’s much more that needs to be said for GlaDOS, but I think tech-wise they could advance it some. Currently players can build testing chambers. It’d be cool if you could build entire complexes consisting of several chambers, with your own (optionally voiced) personality core running the tests. Then the base game could pick up between facilities and whisk you away to new testing places. Basically, make it easier for players to make their own full mods. Especially if you allowed custom hooks for your ins and outs between facilities.