That sounds like it's got potential !

To me, Web3 is about the ownership model rather than the level of technical decentralisation. I appreciate that's probably slightly wrong and highly simplified, but the view I take is that if it's primarily owned by it's users and (more relevant) can't be controlled by a corporation or government, it's Web3.

For an in-house Discord replacement, I don't know whether anything posted would be significant enough to need to be stored forever on the blockchain - perhaps Hive Engine could be an option instead, or even just a bunch of servers doing data storage. From a user perspective, what's going on behind the scenes is less important than the functionality, reliability and user-friendliness.

The hard bit is probably to get enough of a critical mass of users that it becomes a default communication method in the way people currently default to Discord.