Mercedes have enjoyed a resurgence this season to return to winning Grand Prix, but team principal Toto Wolff is excited by the idea of a rival outfit joining the best crews. The Silver Arrows stomached their first winless season since 2011 last year with the Brackley squad still yet to get a grip of the ground effect regulations. Mercedes seemed set to see out another frustrating time this term, too, before turning a corner with their upgrades at Imola. Continued progress with their W15 package saw George Russell win the Austrian Grand Prix in June, thanks to Max Verstappen crashing with Land…