I am Candadian. I started with my employer 7 years ago and was on TN visa until end of 2008. In 2008, I switched to H1B and started my Green Card process. My I-140 has been approved last year, but my employer is starting to have financial problems and I am not sure how long it would be before I lose my job. If I cannot find a new employer that can sponsor me, can I switch from H1B back to TN? Is that possible since I showed intent to immigrate with the approval of my I-140? If it is possible to switch back to TN, what is the process do do that? Do I need to get the Visa at the boarder or can I have the new employer do it while I am in the US? Lastly, if I switch to TN, can I switch back to H1B in the future? If so, is there a time restriction on when I can do that?

Thanks.