I've said this before, but I don't think winning 3 GTs in a year matters much in the sponsor search. If they win the Vuelta you won't suddenly have a potential multi million euro sponsor thinking: oh wait a minute, this is actually a pretty good team. If nobody's interested by now, they won't be interested by next month either.
I don't think their results are the problem, it's who gets these results. They're somewhere in the middle between a Dutch team and an international team. For a Dutch domestic sponsor the international stars aren't that interesting, and for an international sponsor the Dutch department doesn't add anything.
I agree they need a Dutch "flagship rider", to get the Dutch public (and Dutch sponsors) fully behind the team.
Problem is the only such Dutch rider around these days is Van Der Poel, and there is no way they are signing him with Van Aert in the team.
But they could of course sell Van Aert's contract to someone like Ineos, Bahrain or Soudal (not UAE), if they managed to pick up Van Der Poel