The 50 value problems in TAoCP
Knuth's scale goes up to 50 (for "unsolved research problems"). Note that the scale is meant to be (roughly) logarithmic, i.e., adding 10 to the number multiplies the work required by a factor, with 50 meaning some so ridiculously large amount of work to be done that it can be taken practically as "infinite".

Fermat's Last Theorem used to be 50 as an example in the preface, with Wiles' proof it is now "just" extremely hard, i.e., it got demoted to 45 in later editions.

So the answer to the question is "no". By definition 50 is the highest value on the scale.