No; Flarum is written in PHP, regardless of what you do, then PHP never was and never will be, a language intended for real time communication. This is where languages like JavaScript, NodeJS and Go usually come in (Along with many many others).
Tho, there are ways to get close-to-realtime behavior in PHP, simulate it, call-it-what-you-will, but do NOT call it real-time, as mentioned by other posters, at heavy costs on resources and load, tho it is possible, then it is under no circumstance recommended, I can't speak for the developers in regards to what they think, might or will do, but based on PHP's intended use, then no, Flarum will never be real time, if so, it's written in the completely wrong language.