[voyou]

"Currently, as long as people are online, there's a certain guarantee that they will see it."

Currently, if your followers scroll through all their tweets, they are guaranteed to see everything you post. The same is true with the new system, as it's described in the blog post, although they might see some other tweets before yours, if the algorithm decides to prioritise them. Perhaps Twitter will later introduce a more Facebook-like system where users have "the option to only see popularly selected tweets", but that's not what they're currently proposing.