1 DSL MODEM + 4G BACKUP ---> 2 CISCO 48 PoE switch's

I was setting up a network where it has a DSL connection, I want to have a verizon 4g backup that automatically switch over if the DSL connection goes down and then if the DSL connection goes online it goes back to the DSL connection. Is it possible to do that?

I will link the picture of the diagram along with the ebay add to the switches I was looking at buying.

Thanks