It would be easy for the adoption to happen if all the team will work together and partner up. I think this will soon be possible once teams realizes they need the community of the other coin to grow bigger. All of the coins, though they have different technology behind their projects can be united for the adoption.
Some projects can be connected without problems, though there is this main reason why wouldn't this happen.
People are creating their coin for the purpose of people investing in them. They want to popularize their idea of a coin, and despite the cause of the coin, people want to earn money. We are naturally greedy, we have our own ways of showing them. If they started partnering up for a certain project, that would be great but there might be a problem in the long run.