回複：bad situation soon

Similar situation. Here are the things I know so far and hope can help.

Three criteria must be met to keep your current GC process going.
1. 140 approved
2. 485 pending 180 days or more
3. same or similar job

Any one of the above is not met, 485 will be denied. You have to start over from H1B, labor cerificate, etc.

140 approval is the key. Without it, the other two won;t work. If you have an approved 140, but 485 pening less than 180 days, employer can still revoke your approved 140, your 485 will still be denied. But most of employer won't do that.

Here is the office AC21 for your reference.
http://www.uscis.gov/files/pressrelease/I140_AC21_8403.pdf

Currently, 140 premium is not available, so no way to speed up. Good Luck...