Can an Insided community (especially with your community powered knowledge base) exist as a bolt on, alongside an online help centre, or for real success, does a company need to commit to the community as the online resource for customer support?

Yes, we have a successful community Q&A as our primary/initial use case as well as Zendesk support and a robust customer enablement (documentation and training) program. Insided/community is a great complement to those other services, promoting self-service via those other help resources and deflecting support tickets that can easily be solved on the community. I recommend checking out what Insided can do via their Federated Search API. For us, it allows us to feed all of our help content (documentation, training, etc) into the community for one consolidated search. For the end user, they benefit from one single search on community. For the organization, you don't need to try to move all your help content onto Insided; you can leave help content on other platforms while still benefiting from how community Q&A (and other community features) can compliment a help centre that lives elsewhere.