I personally think bitcoin has the chance to decrease in popularity due to its unwillingness to be green. A lot of the world is realizing right now that protecting the environment is paramount and tend to take the easy route of blaming high energy use products, such as bitcoin. I personally don't see how this is as big of a problem with bitcoin as it is with how we have chosen to make energy as a society, and arguing against the usage of bitcoin is futile as it would be nearly impossible for many large democracies to ban it outright at this point. That being said, I could see a large number of users favoring ETH and other POS coins instead just simply due to their arguably equivalent or greater level of utility in addition to being much less resource intensive. It will be many many years before bitcoin even is disussed as anything but the top currency, but its dominance has been waning for quite some time and it may lose its place as the highest marketcap coin one of these days. Its all speculation, but that is how I see it!