As with every moderately sized app, there is bound to be a number of things that Pitch has its own spin on. Different enough for you to matter? Maybe not. Different enough for someone else to matter? Probably yes.
Other products are usually spin out into their own companies and/or under Alphabet rather than Google.
After seeing them close down a couple of services I never thought they would close down, I don't think anything "free" is off-limit right now. Especially depending on how the US/world economy goes.
I know Google kills off stuff left and right, but Gsuite has huge penetration in business and academia. Slides are a part of that.
But it seems like no one cares about web/collaboration in iWork apps and apple isn‘t really pushing it as a gsuite competitor. The sharing model is maybe not exactly work friendly.
So since gsuite is absolutely dominating iWork already, I think they have a shot by just making it more well designed than Slides.