Can I comeback to US if my I-140 is not approved after 6 year completion on H1B+L1B

I have only 15 months left for filing my Green card. My employer will start my PERM procedure in June’2017.

I am thinking about the following worst case scenarios.

  1. What will happen if my I-140 is not approved at the end of 6th year(4.5 years on L1B + 1.5 years on H1B), can leave US for few months and can I enter back into US again once my I-140 is approved ?

  2. My 5th year will complete in July’2017 but my PERM will not be filed before that but it will be filed in Oct’2017. If my PERM/I-140 doesn’t get approved at the end of 6th year then can I re-enter in US once 365 days is passed to my PERM filing date in Oct’2018 ?

So they will they start the green card process (prevailing wages, job description & advertisement etc) in Jun 2017 and actual PERM will be applied in Oct 17?

The plan should be that you leave US when the 6th year completes and PERM hasn’t been pending for at least 365 days. Once that time has elapsed, apply for 7th year extension and return on its approval. Hopefully PP would have been enabled by that time.