My feeling is that Al-Qadsiah will not be satisfied with just signing Nacho and they will likely add new ammunition to the striker and midfielder positions.
They already have big names in those positions, for striker they have Luciano Vietto & for midfielder they have Andre Carillo, but because they're a promoted team that will play in the SPL in the next season, I'm sure they will bring in other top players, no in the midfielder or striker position, maybe it's a goalkeeper or another defender (especially CB). However, so far I don't have any new information regarding the Al Qadsiah transfer rumors and which players might go to this team.
As a team with promotion status, Al Qadsiah definitely wants to show that they can compete even though this is their first season. And one of the things they did was to recruit several players who had big names, especially those from Europe or who now played in big European teams. This kind of thing is something that I think is an instant process that they want to do, because it will take time if they build the foundation from the ground up. But they can do that at the same time as they bring in well-known players.
I think they have a good financial situation, so they make moves like this. Actually, this is nothing new, because most of the teams in the Saudi Pro League are known as teams that have good financial standing.
I wouldn't be surprised if they announced or there were rumors about them being interested in a big name player. The reason is that from the start of their movement, it was clear that they really intended to do that. So let's wait to see what they will do next.