or, someone may have found his wallet files. or maybe he is still around...

quantum cracking wallet keys is the lowest probability explanation.

the thing is, he did use a secure cryptosystem. the ripemd160 address hash addresses it's literally 96 bits of brute forcing there, that is well over 1000 years worth of work with current tech (by which i mean all computers, and all computers added to that projected outwards until that amount of time, which is very optimistic anyway), to pass the "50% odds" mark.