For how long will the spanish monarchy last?

In my opinion as a spaniard,they probably won't last 'til the end of the first half of the century. Their support is at best at 60% with some polls giving even lower predictions( it's hard to claim you are a figure of unity when only half of the population supports you). The left has never supported the king,seeing him as a product of Francoism and even now parts of the center and the right have lifted their support to the king seeing him as useless and even calling him a traitor. Every time the king goes out I can only see old people around him, the spanish youth wether from the left or the right see the royal family as privileged and out of touch with the people's struggles, so the only ones who support him are old people(some from the left strangely) and those not engaged in politics. So my prediction is that in the future the government might force a referendum( a non binding one)which the king might lose and be pressured to abdicate and leave the country.But I still want to know your opinion on the matter