Thus I also begin to wander if in the future, Cruisers will still be exist on World Navies classification.
I wish you well in trying to impose a system of classification on any basis other than "a ship is whatever it's navy chooses to call it". That said, it's quite likely that cruiser will get another run, and another still contradicting the previous, just as have definitions like "frigate".
There are just too many conflicting definitions, historical and practical
Ships classed as frigates have had as little as a couple of hundred ton displacements, 20 guns and no anti-submarine role whatsoever. They were among Nelson's most valuable naval assets.
German "torpedo boats" in WW2 had greater displacements than many RN destroyers, and armed with four 5" guns were just as capable. Late war versions were armed with 105mm AA guns and intended mainly as AA ships. The vessels used by Germany which a
US Navy sailor would call a torpedo boat would be an E-boat to an
RN sailor, or a fast boat (Schnellboot) by its
crew.
@Redlands18 has noted the tendency to growth in size over time, whatever type of ships are involved.
Roles have evolved over time. Technology has changed over time. Doctrines have changed over time. Definitions have changed to meet all of those changes, and will, like them, evolve further in the future. I really can't see, for example, the United Nations writing a definition for Corvette, Frigate, Destroyer and so on, and anyone electing to stick with them beyond the point where they make no sense to their own navy.
I think that in these confines - Defence Talk - we can call them whatever we want if it makes it easier to undestand in some fashion.
Just don't expect that to survive the next technological change that redefines roles and alters sizes, or the next politician wanting to exaggerate his nation's potency or hide it, or the numb skulls of the press who will call all of them battleships anyway
oldsig