An Opportunity for a 21st Century Spanish Republic? The King has abdicated, long live the Republic!

Today's news that King Juan Carlos I is stepping down and abdicating the Spanish Crown in compliance with Art 57.5 of the Spanish Constitution is bound to prompt significant speculation about the future of Spain as a State.

With all (regional) nationalist tensions on the rise and a massive loss of support of the royal family in recent years, it should come as no surprise that many Spaniards would like to have a referendum on the basic structure of the State. I am certainly one of them.
In my view, only a Republic can seriously ensure that we are all equal under the law (in the Spanish case, this would suppress the aberration in Art 56.3 of the Constitution, whereby "The person of the King is inviolable and shall not be held accountable"). In the 21st Century, this simply makes no sense and undermines the basic principle of equality (recognised in Art 14 of the Spanish Constitution). As put in a rather extreme and poetic manner by Diderot, “Men will never be free until the last king is strangled with the entrails of the last priest.” This remains true, particularly in Spain. But there is a pacific way out now.
Moreover, a referedum on the structure of the State would most certainly allow for a deep discussion of the internal organization of the Spanish State and strengthen the importance of its belonging to the European Union (two points not addressed in the current Constitution: the first one, due to the delicate balances that were necessary to overcome the dictatorship and, the second one, due to a lack of maturity of the political system when Spain joined the EU). Most internal unbalances could be settled and the structure of the State could be adapted to the needs of the 21st Century, with much more local devolution, a streamlined and simplified federal government, and a clarification of the regional inclusion in the European puzzle.
Some will say that Spain is not ready for such type of debate and that it would only bring a risk of fracture of the State. If they manage to persuade the citizenship that continuying in the status quo and welcoming Felipe VI is the adequate way forward, then Spain will have a King it will deserve... but this will mean that Spanish society keeps rooted in a value base that does not really encompass modernity and is definitely not in sink with the advanced country it aims to be.  However, I hope this will not be the case and that there will be debate, a referedum, and a significant reform of the State. The King has abdicated, long live the Republic!