Could this defense be the next historic defense next to the 2015 Broncos?

No. Tennessee isn’t lighting the world on fire offensively. Oh, and they allowed almost 5 yards a carry so definitely no
You need to actually look at the plays and not just the average. Henry didn't get a carry on their first drive following the fumbled opening kickoff. On their second drive, his first four runs got 6, 6, 6, and 18 yards for a total of 36 yards which was 57% of his entire day. This was half way through the first quarter.

The rest of the day, he was completely shut down. He had one run over 5 yards....overall 11 rushes for 27 yards which is 2.45 YPC. How many teams do you think have done better against the best pure rushing RB in the NFL?

Spears came in and had one good run of 17 yards which was likely due to the defense expecting pass with Henry not in the game (it was the first carry Spears got).