questions about what happens if I cancel only my internet and keep the streaming service

Thank you.  I don't understand all of your answer.  But I have another questions first.  I have the Super fast internet at a cost of 106/mo.  The description says download speeds up to 800 mbps.  the speed test currently shows 385.  In the last year, the speed has not gone above 400.   If I change to a lower speed (under 800) will my actual speed go even lower? 

Question on my current box - it is 4 years old.  I provide the modem or broad cast element - Netgear.  My Desk top is connected directly to the Xfinity internet.  The broadcast modem is for internet on the TV and my mobile phone (Verizon).  The box I have does not have a DVR.

The part of your answer I am not understanding - "  Xfinity Stream app but when you're connected to another network, or a neighbor's, a public Xfinity WiFi hotspot, or a mobile network, you can only watch DVR recordings and TV Go content you can find that option in your stream apps guide filter. To access your full line up a box would be recommended without Xfinity home internet. As for a new box, the depends on how old your current one is most of the wired TV box options will work with another provider service however some functions and apps on the box may not work with our Xfinity home network."    I don't understand what this means.  My TV is directly wired to the Xfinity cable.  The cable was already under this rental.  I don't know how old it is.  The installer did not suggest replacing it.  That may be the problem with the internet speed.  I hope you can help.  Thank you.

Sorry for the confusion. I believe the confirmation would be that the Stream app would only be able to provide the full channel lineup while connected to the home WiFi network.

Thank you.  I am going to try the installation of the fiber optics service and see how it works.  I have regular cable that I plan to keep.  The installer said that he could look at my system prior to installation to make sure that everything would work.  I have a large box for cable with the cable charge separate from the internet charge.  The box is approx. 11 x 11 x 3 give or take.  I understand that this is too large to be a streaming box.  I think that is where my confusion has been and how I confused you as well.  Thank you for your help. 

@user_flamingomania  Sounds like a great plan. I once lived in a place where we had multiple service providers.  I have a link I would like to share with you. This link contains the compatible devices that works well with the XFINITY Stream App such as a Firestick, Smart tv etc. https://www.xfinity.com/support/articles/xfinity-stream-app-faqs.

We can clear up that confusion. My boxes are different sizes. Can you take a look at this link https://www.xfinity.com/support/articles/x1-hub-vs-companion-box and let us know which box you have? This way we can confirm the box you have at home.