It's possible but extremely unlikely. Due to the nature of how the gaming world is constantly changing and other newer, better, more competitive games are being released year after year, blockland, being unable to change or improve itself, simply cannot compete with the newer and better games on the market.
That being said, retention of the current userbase is 100% doable, provided that players actually invest time in creating content and making fun servers to play on, rather than going around trolling, cheating, being toxic, and crashing servers.