Field theory & strings can also be divided into classical (“phenomenological”) and quantum, so each 2semester course can be taken in parallel, rather than series; the classical halves can then also be taken by nonspecialists. For example, for someone planning on going into strings (nonstring theory students would modify the 3rd semester):
semester  Mechanics  (Semi)Classical fields  Quantum 

1: core 
Classical mechanics  Classical electrodynamics*  Quantum mechanics* 
2: core theory 
Statistical mechanics  Standard model

Quantum field theory

3: specialized 
leftovers  Supergravity & branes

Strings

4: other 

Other specialized 3rdsemester courses would include “Advanced” courses in Particle Physics, Field Theory, & Statistical Mechanics.
(Presently, the only viable plan for students of string theory is to take quantum field theory in their first and second semesters, so they can take string theory in their third and fourth.)
*Ultimately the 1styear courses could also use some improvement: In particular, there is considerable overlap between conventional "Classical electrodynamics" and "Quantum mechanics" courses, as both are mostly about solving wave equations (linear in the wave function, in fixed backgrounds, including boundaries). A better dichotomy might be:
Wave theory

Quantum theory
