Not very often. Here is the firmware version history I've recorded on my Tivo's Scientific Atlanta / Cisco / Technicolor PowerKEY cards:
Sat 02-08-2014 firmware Ver: PKEY1.5.2_F.p.3001
Thu 10-16-2014 firmware Ver: PKEY1.5.3_F.p.1201
Thu 11-10-2016 firmware Ver: PKEY2.0.1_F.p.0901
Thu 09-08-2017 firmware Ver: PKEY2.0.1_F.p.1101
Like yours, it's still showing PKEY2.0.1_F.p.1101 today, so no update for the last two years. My guess is that this matters more to Comcast (for content protection) than it does for customers, but "guess" is the operative word in this sentence!