As long as you have no data caps, battery life as long as a laptop when tethered, and a fast connection I would agree. At some point in the future and then we can get rid of the added cost of wifi as well.
No data caps some providers offer a set amount of Gigs at LTE and then drops the speed but still unlimited. This is more of a problem with carriers being cheap. Wifi through a landline will always be cheaper, not going to get into the details as to why this is, but that is what it is at present.
Sure; which is why I contend that if 5G truly lives up to its hype as wireless broadband it will change how connectivity is delivered. One 5G account linked to multiple devices can replace fiber - modem - wifi as a the way one connects to the internet. Once coverage in cities gets ubiquitous there would be no need to find hotspots and constantly reconnect; you simply stay connected to your 5G provider.
Two forms of 5G and this will only complicate matters as some carriers support one or the other and some both depending on cost, plus not in all areas and to pay for the higher cost to upgrade all 5G users will feel the $ increase in plans. 4G/LTE will still be a backup and most 5G users unless in a supported version or coverage area will be paying for 5G only to receive 4G/LTE most of the time.
Will 5G in all connected devices be possible and available, “eventually” however what we have seen is that even with the rollout of 4G/LTE the cellular space is just a mess. 5G is not going to fix this.

No need for BTO, everything has it and the costs are spread over many more units, and with the deletion of wifi it could even be a wash.
Carriers don’t see it that way there is a reason why they charge you $5-10 to add a cellular AW. In a carriers eyes it is how to charge you more to provide less. To add an AW to your present plan should be no different to a tethered device, considering an AW is not a main device and it’s present capabilities is limited to a larger device like a phone or tablet.
I like your utopia of having a single account and adding let’s say up to 5 cellular devices and pay one price similar to having an internet connection at home and adding more wifi devices to your router, however carriers see it as an opportunity to charge more. What if I only want cellular on my AW but not phone as I may want to tether if I really need to, guess what no option is available. Ever wonder why?
Much of the value depends on what you get for the cost. For $10/month I get unlimited data on my iPad; if I tethered to my phone I have a data cap that I would quickly burn through.
This is more of a carrier issue being cheap than anything else.
In Estonia for example you can get a PAYG 4G/LTE data plan for under €5 for a two week period, this my have changed since I last got it, however you get 50GB and you can tether if you want to as many devices as you want.
Depending on country and carriers, most are cheap and rip off they “loyal” customers. 5G is not going to make things cheaper, it will make it more expensive while you get lower speeds most of the time.
