Honestly don't see it as a huge deal. Irvin has shown next to nothing. Wasn't known as an adept blocker or particularly strong TE. The biggest blow is just losing some (minimal) TE game experience and now counting on guys who aren't as familiar with the system.
Polendey is 6'6 245 and is supposedly more adept at blocking than anything else. Maybe Patchan (6'6 255) can get some situational reps at TE if needed (while being primarily DE)? Like many have mentioned, brining in a 6th OL in running situations is a good move.
We all know Mallory and Jordan are insanely talented, but they need time to get comfortable with the system and be dependable. However, from a physical standpoint, Jordan is ready.
Obviously, I'd rather it didn't occur. I feel bad for Irvin. But, I'm not overly worried about this.