It will definitely matter its his legacy as the coach of Italy. The NT means a lot to Italians and especially to people like Conte.
Conte was supposed to lay the foundations for the new azzuri in his short tenure. This requires integrating the best Italian players today who will be playing in the next world cup if not the next Euros. Marchisio and Verratti should be THE backbone of the new azzuri and now both are missing. This means that even if they do well in the Euros using De Rossi, Motta, Pirlo, Motolivo and the likes, the whole purpose of his tenure won't be achieved. Whoever takes charge next will have to build a new team around verratti and marchisio. The most Conte can achieve now is to determine the new front line of Italy for years to come. Midfield and defense will have to be done by someone else.
They were brilliant to be honest. Remember how thin our bench was in 2011/12? That season would have been impossible had any of marchisio, Vidal or Pirlo been injured.