On the Gsync going away because it is a "proprietary tech": proprietary means nobody else can use that technology and as Acer, Dell, Asus and others make Gsync monitors that is not obviously true.
Thats not what proprietary means in this instance. Nvidia developed and own Gsync technology/brand/rights.
Monitor manufacturers must pay Nvidia for the use of the Gsync module in their monitors. Only Nvidia can legally manufacture and supply to monitor manufacturers (or have others manufacture on their behalf) the Gsync module.
The actual cost of the module itself will be minimal in comparison to the premium Nvidia ask for its use by monitor manufacturers.
It represents a great profit margin for Nvidia, which is why they are unlikely to implement Vesa variable refresh rate support unless AMD GPUs become a more compelling purchase over Nvidia than they have been to date.
For now, enough people are willing to pay the extra ~£150 over a freesync monitor/GPU combination to make it worthwhile Nvidia keep going with Gsync, even though the only real advantage over Freesync in most cases is Gsync's lower supported minimum sync rate.