Moving from L1 to H1

[vishwaq3]

I am currently on L1 and I have an approved H1 from the same company from Oct 1, 2012. I have other employers ready to transfer the H1 in their name from Oct 1. My company has a 2 week notice period so if I have to start on the new company from Oct 1 I have to resign by mid September which means I will be still in L1. If the current employer decides to relieve me the same day should I go back to India? is there a grace period? Can they withdraw the H1?
What should be my ideal plan of action