The answer for the next letter in the sequense is "L"

Assigning numbers to the letters gives 2, 5, 10, 17 which progess by the incriments of prime numbers.  The next letters match the rest of the sequence if the letters are repeated once "z" is reached.  Corresponding to "b, o, f, y" is 28, 41, 58, 77 and then followed by 90. 

Dividing 90 by 26 gives a remainder of 12.  The 12th letter of the alphabet is "L".