In 2 years there will be nothing left from the FFPs at this rate, there is a crazy race to the bottom and complete devaluation of miles. Two years time is a long time to predict which of the currently terrible ffps will be the worst. One suggestion would be to at least diversify to 2-3 programs, and get some status in 1-2 alliances.

But the main thing you have going for you is that you can be flexible with time, so you could book trips potentially at their lowest mileage rates.

You could also probably do better with paid rates in Y and J, as you get closer, just be on the looked out at the 1-year mark for really good deals, like the current $200 Y fares to Europe. It may be better to get some of the trips in paid fares, as a lot of good deals exist, and they are better value than miles.