Obviously Desantis isn't someone like Walker, but since 08, a large number of front-runners have imploded. Whether it was Paul, Bush, Cruz, Rubio, Giulani, etc. The only exception is Romney and that had more to do with Perry's poor performance.
You really need to examine these contests in terms of lanes or paths. A lot of these candidates we are discussing that collapsed were either jostling for their lane with someone else who had other advantages or their lane was too narrow to be nominated at all to begin with.
I would argue that Mike Huckabee, Rick Perry, Newt Gingrich, Rand Paul and Ted Cruz were all rather unlikely to be the GOP nominees in their cycles because of baked in demographic limits to their paths, and the mood/desired direction of the party after Bush. The GOP wanted to move on from Bush, but they wanted someone more fiscally (and a touch less socially) conservative, more hawkish on the border and more outside of Washington. By 2016, with war weariness reaching into the depths of the GOP as well, a more restrained foreign policy was craved.
Romney's appeal in 2008 was far too narrow to win the nomination and he managed to piss off everyone and their supporters over the course of the contest, ensuring everyone would rather someone else be the nominee and not him.
In some ways it would have been nice if Perry had not collapsed in 2011, because Romney's strategy was to go after him for his comments on social security, Texas secession and of course, Immigration. I can see Romney just obliterating Perry in Florida the same way he nuked Newt there. Romney dominated the establishment by virtue of being "his turn", he had the money behind him and he had the immigration issue as his ace against any base candidate, with the exception of Rick Santorum who surged way too late and once again had far too narrow of a base though he did force Romney to make his tax cut plan more aggressive to win the Michigan primary.
Scott Walker and Chris Christie were never going to be the Tea Party activist candidate because Ted Cruz had a natural advantage over that space and in terms of the opposition to that lane they all preferred to compete with each other and with Jeb Bush, John Kasich and Marco Rubio as well for the remaining sliver of the party that was up for a return to the Bush/McCain years in terms of foreign policy and immigration. That left a massive space for Trump to claw to a plurality lead and no one really competed with him for that space, only attacked him for the positions he took, essentially hardening his base around him.