New York CNN Business  — 

Every year Facebook hosts a multi-day conference for developers that doubles as a splashy press conference for new features and products.

But not everything that comes out of its F8 event comes to fruition — or at least not in a timely manner.

Although some announcements like virtual reality friendships and chat bots still exist on Facebook’s (FB) platforms, others have been quietly scrapped.

Ahead of this year’s F8, which kicks off on Tuesday in San Jose, we are looking back at some of the big topics yet to become a reality.

1. Typing with your thoughts, hearing with your skin

At F8 2017, Facebook said it was working on technology that would let you type words directly from your brain and “hear” through your skin. The company said it would read your mind via sensors and optical imaging, and translate that information into words.

At the time, Facebook said a team of 60 scientists and engineers at its secretive “Building 8” lab would be working on a prototype implant device over the next two years, and that it would be tested in a medical setting. The long-term goal was to launch a commercial device that wasn’t invasive.

Later that year, former DARPA and Google executive Regina Dugan who was leading the project left after 18 months. Not much has been said publicly about it since, but the technology appears to still be in the research phase, according to a recent research paper published by academics with a grant funded by Facebook.

2. Clear History tool

In the aftermath of the Cambridge Analytica scandal – where a political research firm accessed information from as many as 87 million Facebook users without their knowledge –Facebook said it would add a feature called Clear History to remove your browsing history, including what you previously clicked on and which websites you visited.

Facebook said last year it would take “a few months” to build the feature, but there’s still no sign of the tool.

Clear History intends to give users information about the apps and websites they’ve interacted with that use Facebook’s ads and analytics tools. People should be able to delete that info from their account, too — once it actually launches.

At a recent press event about “integrity” on the platform, Facebook executive Guy Rosen said the tool had been pushed back to this fall.

3. Facebook’s personal assistant M

Last year, Facebook shut down M, its automated personal assistant meant to be a text-based rival to Amazon’s Alexa voice assistant or Apple’s Siri.

Facebook is always coming up with new ideas. Not all of them make it.

M wasn’t announced at F8, but some of its capabilities and big updates were: In 2018, Facebook launched translations by M in its Messenger chat app. It could translate English to Spanish and back for people talking over Facebook Marketplace in the US.

M may be gone, but Facebook recently confirmed it is working on other AI-powered voice assistant technology for its Portal and Oculus products.

4. Facebook Dating

Facebook’s dating platform, announced at last year’s F8 conference, has been in a testing phase in several countries, including Colombia and Canada, but it hasn’t expanded to the United States yet.

The company said people will be able to use their first name to set up a dating profile on the platform, but it won’t be visible to friends and will not show up in News Feeds. Facebook Dating is opt-in and users won’t be matched with friends.

Facebook Dating was expected to roll out by the end of 2018, but that timeline has come and gone.

Perhaps this year Facebook could revisit some of these ideas, or it could come out with all new ones that might never see the light of day.