it's incredibly repairable. I still use the t480 for modern workloads because I've been able to switch out the battery, the fan, the keyboard with fairly abundant aftermarket parts.
Yes, whoever can shrink this down to the size of something that would fit in your pocket would make a killing. Imagine not only being able to make phone calls, but use productivity software and even browse the internet.
If you connect then to some battery pack with a USB charger, you have a mobile solution, though one more cumbersome than a real smartphone.