Large players currently can grow, buy, or merge without any oversight. If that continues the prediction might be right. But there are many unknowns. Facebook and Google rely on advertisement. If the technology for blocking or removing or filtering adds gets better and more wide spread, that revenue might dry out. On the other hand these players are so large (similarly like Amazon, Microsoft or Oracle) that they can diversify and buy up new technology, surviving in other sectors , even so the original sectors dry out.One has learned from the lessons of the past. Its very hard to predict the future in technology. Most experts in the past were dead wrong. examples.