Using two MOSFETs altenatively ON/OFF to simulate DC operation in the linear region?
All your circuit achieves is a reduction of the time spent for each MOSFET in its linear region. In fact, you could use both circuits in parallel fed from a common input voltage that is half the voltage necessary to produce the same current (should only one circuit/one MOSFET be used).

This has the effect of properly sharing the current equally between MOSFETs but it doesn't totally mitigate against thermal runaway (due to conduction in the linear region of a MOSFET); it just halves the problem. However, it is streets ahead of just paralleling MOSFETs and hoping for the best.