PHILADELPHIA — One of the main questions about the Eagles these days — inside and outside the NovaCare Complex — has suddenly become whether or not Nick Sirianni will survive his team’s end-of-regular-season collapse, and whether Monday night’s wild-card playoff game at the Buccaneers will be a referendum on his ability to lead the team. The vibes around the Eagles have gotten bad. Typically, teams that sink to these depths are losing ones that ultimately get coaches fired — not ones with 11-6 records who are heading into the playoffs for a third year in a row. Just two months ago, Sirianni wa…