It would be better if there was a clear timetable published, but there has been a logical progression over a number of years towards the inevitable phasing out of MT4. Products cannot be supported indefinitely.
MT5 developed --> nobody forced to the platform
MT4 language updated with backwards compatibility --> start the migration of MT4 users to MT5
MT5 issues fixed (like hedging) --> make it more appealing
Older MT4 unable to compile on newer builds --> force the reluctant ones to catch up
MT4 removed from MetaQuotes site --> an indirect statement of intent
No more development or bug fixes on MT4 --> encourage customers (the brokers) to move over to MT5. Brokers bear the brunt of customer support
Brokers will need to make the final migration, but MetaQuotes have made their intentions clear IMHO. These are the twilight days of MT4.
I don't sell anything. I only say what looks like obvious. I think, most of the brokers purchased their MT4 licenses many years ago. Currently MetaQuotes is selling more MT5 licenses than MT4 licenses. MT4 is a mature market, not a growing market. Almost all brokers already have their MT4 license, therefore, MetaQuotes will sell very few MT4 licenses in the near future.
The word is, they cannot stop servers within 6 months or a year without a fool-proof migration program for million users. And AFAIK they do not have such a program. There is neither any message from MQ they would stop the MT4 servers, so I wonder how you come to that 6 months or a year estimate.
Once brokers start shutting off MT4 servers (which will happen - why would brokers want to provide a 3rd party product to their customers (traders) that is unsupported?) people will move to the other platforms being offered by the brokers.
The die-hards may jump over to another broker still offering MT4 but that is simply delaying the inevitable and ultimately they will run out of the brokers willing to work with an unsupported product.