Paramount+

https://www.viacomcbs.com/press/viacomcbs-announces-march-4-launch-date-for-paramount

Paramount+ will include content from CBS, Nickelodeon, Comedy Central, MTV, BET, Smithsonian Channel and Paramount Pictures, as well as Paramount+ Originals.

It's the ViacomCBS rival to NBCUniversal's Peacock and WarnerMedia's HBO Max, as well as competing with the likes of Netflix, Amazon Prime Video, Disney+ and Discovery+.

It very much seems to be a rebrand of CBS All Access with not too much more than what's already on there. Interesting that they're still not including Showtime in this, you'd think that would've made it more competitive with HBO Max. It's pretty unfortunate that they were really ahead of the curve by launching this in 2014, long before the recent streaming wars, and yet it doesn't appear to have made much of an impact, other than Star Trek. That rubbish name probably didn't help, Paramount+ is much better.

You're right about Star Trek - three simultaneous shows, that never even happened in the 90s - Deep Space Nine launched when Next Generation was already a few seasons old, then Voyager replaced TNG, and when DS9 ended it wasn't replaced, with Enterprise launching only after Voyager ended.

TBF the current Star Trek series are very different to each other so can co-exist without cannibalising each other.

I would expect Paramount+ will end up co-producing shows with broadcasters within the wider ViacomCBS family.

It'll soon be up to five(!) once the Pike series and Janeway cartoon are launched... though the later will be under the Nickelodeon banner.

However, unlike Trek of the 90s... these series run much shorter seasons, and aren't being released at the same time anyway. So they never really end up in a position of needing to compete with one another. Pretty soon they'll have enough new Star Trek to air new episodes all year around.

A problem with the international expansion is that they’ve already largely licensed the existing Star Trek series elsewhere (Picard and Lower Decks to Prime, Discovery and the back catalogue to Netflix) so running the marketing on being the home of Star Trek won’t be an option. I’m sure they’ve plenty of other content they can run with, mind, but Star Trek would have been a crowd puller.

In the case of Australia, they're simply rebranding 10 All Access and adding more ViacomCBS content.

They've said they're keeping it as a standalone service to protect the "boutique" feel. That is presumably a slight dig at HBO Max which has been widely criticised for diluting the legendarily prestigious HBO brand.

Released
Star Trek Discovery 1-3 (4 filming now)
Star Trek Picard 1 (2 filming in feb)
Star Trek Lower Decks 1 (2 in production)

Coming soon
Star Trek Strange New Worlds (filming now)
Star Trek Prodigy (audio recorded, being produced now)
Star Trek "Section 31" (pre-production)

Yeah, why didn't they call it WB Max? HBO's name is so prestigious that Sky Atlantic used it as a selling point when it launched (the home of HBO).

A trailer for Paramount Plus aired during the Super Bowl:

Maybe it's so they can leverage the reputation of the HBO brand (also, HBO Max is one of the most expensive of the major streaming services in the US).
Regarding the possible dilution of the HBO brand on HBO Max, original content is split under two brands: "HBO Original" (most of which is also available on the HBO-branded linear channels) and "Max Original" (all the non-HBO content produced for the service).