For me nothing replaces the desktop experience.
I know many people don't use desktops anymore, heck casual people are using their laptops less and less. I for one still use my desktop and will continue to for the foreseeable future. The desktop simply offers a better experience in my opinion as you have a big screen, big and easy to use controls, no need to worry about some stupid battery, no need to micro manage storage and the performance is always a step ahead everything else.
Time to upgrade? No problem you probably only have to change a few components and not the whole thing. This is the beauty of the desktop only those who have done it will understand.
But but you have to sit on a chair and table? Well yes because you need a table for the most convenient input solution known to mankind aka keyboard/mouse. And about the chair part well just get yourself a high end one, sure it won't quite be like laying down on a couch but you will not really miss it either.
A properly set up desktop still gives the best internet experience as far as I am concerned.