“in 50 years, what will the best mathematicians think about it?”
How do you make a priori judgments on who the best mathematicians are going to be? In your opinion, what qualities/achievements would put someone in the group of best mathematicians?
Anyway, I think that if one adopts this perspective and takes a careful look at current research using Bayesian reasoning, one is led to the conclusion that almost all of it will be considered to be irrelevant (confidence ~80%).
How different would your deductions be if you were living in a different time period? How much does that depend on the areas in mathematics that you are considering in that reasoning?
Your standards seem unusually high. I can cite several highly interesting and original work by mathematicians who would most probably not be in your, or any top ~200 list. For example,
Recursively enumerable sets of polynomials over a finite field are Diophantine by Jeroen Demeyer, Inventiones mathematicae, December 2007, Volume 170, Issue 3, pp 655-670
Maximal arcs in Desarguesian planes of odd order do not exist by S. Ball, A. Blokhuis and F. Mazzocca, Combinatorica, 17 (1997) 31--41.
The blocking number of an affine space by A. Brouwer and A. Schrijver, JCT (A), 24 (1978) 251-253.
I would like to know more about the perspective you claim to have gained which makes you think this particular way.