Even at $6.50 they're too expensive to be reasonable for use on a $35 computer. Get them down into the $1 range and then they'd be reasonable.
I definitely see the USB type-C on the PI. Its not a question of 'if'. Maybe a small question of when, but the main question is why - and I think the answer to that is all the following ports can be made into USB type-C and hence cut down on the number of ports (given that it can supply power and data simultaneously): micro-usb power, hdmi, ethernet, usb 2.0 ports, audio jack. Now you can shrink the size of the board, or throw in more hardware in the space obtained. Maybe integrate more memory, controllers.
And require everyone with existing cables to have to replace them? Not bloody likely. A major virtue of the current connector set is that, by and large, many people have workable cables on hand that can be repurposed for the Pi. Switching to USB-C any time less than 5+ years would mean effectively requiring the purchase of a full set of cables for every connector. The Pi sitting next to me has 5 cables attached, plus a WiFi dongle (which would take other another cable as an adapter or a whole new dongle) and a USB stick (again, cable or new device). So...5 to 7 cables. At the price given that would be $32.50 to $38.50, or roughly the cost of the Pi itself. Now considering that 2 of connected cables are for the keyboard (it has one that cost $15) and the mouse (a $30 trackball), one might wind up paying nearly twice the cost of the Pi itself.
As for more memory...not going to happen unless a different SoC is used. The BCM2836 is maxed out at 1GB. Adding more circuitry on the board would increase the cost of the board (and there is no indication that USB-C connectors are any cheaper than the ones being used now), so where are you going to find the cost reductions to add new hardware? (Granted, if additional hard *were* to be possible, it's very likely that the only possible one would be an RTC, and that is an addition I'd love to see.)