After 31st March 2021, it will no longer be possible to upload courses but it will still be possible to play courses that were uploaded before the service discontinuation.
While you would think most fans of the game would have moved on to the sequel by now, there is one player by the name of Braden “ChainChompBraden” Moor who is still attempting to complete a single run of their own insanely hard course, so they can upload it to the game's servers before they shut down next March.
This same individual has already spent "3,353 hours" over more than four years trying to beat their level, Trials of Death:
Here's what Moor had to say to VICE since Nintendo announced it would be shutting down the game's servers last week:
"Some people saw it [Mario Maker 2] as a deadline since inevitably a large portion of the community would be moving on. The project was always intended as a personal challenge, but this was the turning point where I fully realized that. And while the bulk of the community did eventually leave the game behind, all the support surrounding me remained"
"People are once again definitely pulling for me to try and get this thing up before uploading is no longer an option, but if it doesn't happen in time for that, the true end goal of me clearing the level is still going to happen. Not too many people were ever lining up to play the level for themselves. They all just want to see the clear happen, and that's still going to be delivered whether it's on the servers or not."
If Moor doesn't beat the March 31st deadline, as noted above - the aim is to still clear the course. After that, a "full overview" of Trials of Death will be released for anyone wanting to recreate it.