Due to decentralised behaviour, it will exist forever.
I believe that Bitcoin blockchain will exist forever but how we can access it, and use our bitcoin for buying, sellings, deals will be very different in the future than now and in the past. When governments nationally and globally put their eyes more closely on Bitcoin, they will enforce more regulations on it, and there will be less freedom to use Bitcoin blockchain without legal issues with governments.
By being decentralized, Bitcoin blockchain will be for everyone but Bitcoin users will have to be more knowledgeable and careful with legal problems in future.
As long as big institutions, whales, and the demand for bitcoin continues to gain momentum, then we can be certain that bitcoin will continue to blossom and grow.
The market does not only have institutional investors but retail investors, traders, speculators and gamblers. They are all important in the market and their existences mean a lot for the market. At different market phases, their activities will be different and more or less active than the others and themselves in other phases.