Consider discarding the CLA if you anticipate third-party contributions. If you need to verify provenance, the Developer Certificate of Origin is a better approach. Otherwise, this (correctly) reads as a project which intends to take advantage of FOSS contributors for a while before pulling the rug and making it non-free again.
I like CLAs. If there's an open source project that I love/depend on, I will most likely want to be able to contribute to it for my own personal reasons at some point (e.g. fix a bug that bothers me or add a feature I want). I am a Sublime Text addict, but hate how slow development is and how resistant they are to adding more dev-focused features. I would happily sign a CLA if it meant I could modify the code myself,…
The only purpose of a CLA like this is to provide for a future where the software can be made non-free again.