As economists, we should be well advised to restrain from making such forecasts. Future is hard, if not impossible, to predict.
For example, take the job reports in the US which are published on a monthly basis. Forecasters, most of which financial analysts and economists, consistently fail to produce accurate expectations, sometimes by a large amount. Latest example with the previous report (20% error). Basically all forecasters of economic growth year-on-year constantly fail and have to adjust their forecast as the year passes by. See WTO and IMF, but also private institutions, such as Fitch or Standard and Poor's.
If economists fail to predict what's going on month on month, or year on year, I don't see how they could produce any accurate and reliable forecasts @15 years.
Furthermore, most models rely on observations of the past and of the present. Such data are a terrible basis to predict the future. Some learned this the hard way, such as LTCM whose risk management and investment policy relied on past observations to predict volatility, leading them to burst in 1998 when unseen volatility did spread. Future is unpredictable and is unlike the past. Notice that a lot of major innovations occurred by pure chance (lasers, internet to some extend, Carambar candies, and so on). Thus, it would be foolish to make guesses on what's going to happen 15 years from now, especially relying on today's data and known facts.
Also note that it is always much easier to predict doom than prosperity. It attracts public attention, and you can always say after the fact a nice "I told you". French economist Jean-Marc Daniel regurlarly underlines this fact in his books (for example Ricardo reviens ! ils sont restés keynesiens, though I doubt it was translated in English.)
If you want some interesting readings (and more) on the topic, I suggest you take a look at the work of Nassim Nicholas Taleb , in particular his book The Black Swan. I also recommand the podcasts hosted by Russ Roberts, with Harvey Campbell, Nobel laureate Peter Hansen, or James Heckman, which deal with the limitations of economics.
TL;DR: nobody has any idea about what's going to happen 15 years from now.