This hits the nail on the head. The new MBP must have TB3/USB-C but I will be astonished if it doesn't feature at least one standard USB port.
This is not like the floppy disk situation. If one excludes TB1/2 and Firewire devices, virtually every peripheral device for the last decade has used USB. Today, in 2016, virtually every external HDD still ships with a standard USB connection and cable. Nearly every person who has bought an external HDD in the last 5 years will expect to be able to just plug it in. Apple has made it crystal clear in recent years that the mass market and not the pro market is their priority.
I am one of those people - mainly due to a love of photography - who is always wanting faster and better cables and monitors. I want TB3 and USB-C in everything and as soon as possible. But given that the two best smart phones in the world are not using USB-C (Samsung using micro-USB for another year at least - and for phones that will be used for a few years at least by most users) and Apple using lightning, it is slow going for USB-C to catch on and will be something that takes a number of years. It (with TB3) is clearly the future for high end - just as Firewire and TB1/2 were and hopefully USB-C will catch on at the lower end - but this is a process that will take a few years at least. In the meantime every single thing that can be plugged in to a computer will be using standard USB. The cables are there in every house, they work fast enough for 99% of people in 99% of situations (and Apple is going after the mass market these days which *always* values convenience ahead of performance - look at the fate of TB1/2). The cables -standard USB and/or micro-USB - can be used with the vast majority (I would guess something like 95%+) of smartphones, external power packs, printers, USB battery chargers, bluetooth headphones, USB charging torches, and perhaps most crucially external HDDs. They are shipping with those devices today in 2016 - in devices that people will buy and realistically expect to be using in 2017, 2018 and 2019.
As I said I would be very happy if tomorrow everyone agreed to move to TB3, bought new cables, got the prices coming down and choices going up. But it won't just happen like that. In many respects USB has been a victim of its own success. USB3 is more than enough for most people and has the same form factor as the USB standard that has worked with all peripherals for over a decade. It would be astonishing, and likely a large commercial error, for Apple to not include those standard ports on the next generation. Imagine millions of people suddenly being told they have to buy an adapter, a hub or a new cable to use quite literally any device and/or peripheral they have bought or will buy this year to even plug it into their new MBP. We could tell them again and again about the improved performance but the mass market isn't like that - hence Samsung sticking with micro-USB for another year. I just don't see Apple taking such a risky decision that would inconvenience and annoy greatly something like 99% of their customers even if part of me wishes they would.
