I believe Expanse will be one of the block chains implemented on a large scale. Expanse has been around for 2.5 years and has consistently been working and improving and now has a blockchain with several Dapps including Tokenlab, an ICO creation and managment platform. I see Expanse continuing to grow, adapt, and expand. I believe with the ICOs being launched on the Expanse blockchain and new Dapps being made on Expanse it will bring a lot of new users and investors and grow exponentially.
Because the cryptocurrency market is still relatively young, an unknown coin today could easily be the next big thing tomorrow. With the pace the market is moving, it wouldnt be a surprise to see a long-term champion that hasnt even been created yet. Larger blocks can hold more transactions which generally lead to lower fees and faster transaction times even as the network scales. However, i think BTC, ETH and XRP are the most likely coin to be implemented on a large scale.