Yes, there is a chance that you will get denied waivers if you switch. But there's probably a better chance that you win't be denied - it really depends on how far out you live from the stations in your DMA. You could call the stations in question and ask them.
I'm assuming that Directv does in fact have national network feeds available for people with waivers?
I'm assuming that Directv does in fact have national network feeds available for people with waivers?