In order to create a more or less plausible forecast for the future of proxy we will need to determine the time and the reason of their occurrence. First proxy servers appeared almost simultaneously with the creation of Internet. This happened due to the fact that in its early days of development there was a need to own an external IP (a unique address that identifies the workstation in the general set of computers) to become a member of Internet community. IP addresses were very expensive at that time and in order to avoid buying external IP for a single computer, many users rented one channel which was granted by a provider.
The release date of the first proxy server is known for sure: it was a Windows-based proxy “WinGate” that appeared in 1995. Since that time WinGate is being constantly improved by a Microsoft team simultaneously performing the functions of the router, firewall, antivirus, VPN and mail server and web cache. At the moment the stable version is 8.5.2 that was released in October 2015.
WinGate proxy server is not free but developed as a proprietary software. That is the reason of longevity and unbreakable axiom of any proxy: shared proxy servers live longer than free ones.
Free proxies usually fade away. However there are happy exceptions - several free proxies exist longer than their counterparts but there is alwaus a great funding source. It may be an enthusiastic patron (sometimes two or even more), or advertising will generate the income to maintain a free proxy.
Another important reason for vanishing even most reliable proxies is the emergence of different sanctions. We have discussed that illegal proxy servers often provide services for criminal aims. Different countries perform the control of such situations at different rates but taking into account the international nature of the Internet we can say that illegal proxies are usually banned.
To summarize we will say that shared proxy servers will obviously keep on existing. The increasing internet censorship makes it necessary to use a stable hub to use favorite sites without being banned. Free proxy services will likely continue appearing (they are created in large quantities) but still it is likely to be solely as advertising platforms and they will subsequently become shared.