I'm afraid it probably won't, if they are used to the JavaScript syntax. Reasonml is also meant to be used in the web more than used through OCaml.
ReasonML adoption automatically means OCaml adoption, because ReasonML _is_ OCaml. People will be learning about and using HM type inference, modules and functors, polymorphic variants, and all the good stuff. Don't let the syntax fool you ;-)
Also, ReasonML itself is meant to target all platforms that OCaml itself targets. Right now the Reason team is focusing on the JavaScript + React use case to prove out the technology and appeal to a wide base. But they also use jbuilder and opam to target bytecode and native. There are no restrictions.
By the way, to the people calling the syntax ugly and its users idiots, please tone yourselves down and think about why OCaml has been around in a niche for 20 years but Rust took off in less than five.