If you "cut the cord" on cable tv, most of the time, comcast raises the price of your internet by ~$30ish (or more) for exact same internet speed, as an "internet only" subscriber... so your apples-to-apples comparison of going with "internet only and streaming" vs. "cable + internet" from comcast needs to take into account the additional price increase you'll take for "just internet".
I'm personally a "cord shaver" rather than a "cord cutter". I don't rent (much) comcast hardware. I own almost all of it. This approach is not for everyone; it's a bit DIY-y and maybe for tinkerer's hobbyists, but that's "part of the fun of AVS Forums" IMO.
I am a Comcast subscriber. I have their 220+ channel cable TV package and (I think) their 400 mbps internet package (the fastest they offer in my area).
I own my own modem. No rental.
I own two (older model) HDHomeRun Prime's (each tunes 3 channels per CableCard). I'd only need one if I only wanted the ability to tune 3 channels at a time.
Comcast provides the first CableCard free-of-charge. I pay ~$8-a-month to rent the second cablecard (and the ability to tune 3 more channels at a time).
I run the HDHomeRun Engine on a QNAP TS-431+ NAS, and it lays down DVR recordings (and buffers live TV) on hard drives I have installed in it.
I have 6 NVidia Shields and one Windows 10 machine hooked up to 7 TVs in the house. I own all of that "equipment" and don't pay to rent any cable boxes or "X1 machines" from Comcast. That Windows10 Machine serves double-duty as a Front-End for HDHomeRun View and a back-end server for Plex (my Blu Ray collection is ripped 1:1 in MKV), Roon (my CD collection is ripped 1:1 to FLAC). and Steam. Those Shields are pretty cool little devices that bitstream the lossless audio from my MKV movies to an AVR, and can play back those Steam games either using my PC or NVidia's Cloud computers. And they run all of my "streaming apps" like Netflix, HBO Now (not Go; I don't subscribe via Comcast), Youtube Red, etc, all on one interface.
This is all "just how I do it". There would be cheaper ways, if your end goal is to just save money, you might be able to win out with a streaming-internet-tv package (like Youtube TV or Hulu TV, etc). The only thing to keep in mind is how much more the internet service goes up if you cancel the TV portion of your package... the savings may not be as great as you think. I didn't like Comcast's hardware back when I was renting it, anyway, and I definitely don't miss the monthly hardware rental fees now that I own my own gear...
Living Room: Sony x940E; Denon x4400h; Ascend Sierra RAAL Tower L/R's and 2EX center, Ascend HTM-200SE Rears, Rythmik F25 sub. NVidia Shield, ATV4k, OPPO UDP-203, CCA.
Basement: Samsung PN58B650 LN-T4065F (x2); Onkyo TX-NR809; Polk Monitor 70 Series II L/R's, SVS PB-1000 sub. NVidia Shield (x2), Windows Desktop, CCA.