Does my Salesforce application have to be built completely from Skuid?

No. Builders can use both Skuid pages and non-Skuid pages in the same application. Skuid Pages can also be included in a Lightning page along with Lightning components, but will often load one to two seconds after native components do.

It’s also good to note that a Skuid license is not needed for every user in your Salesforce org. However, a Skuid license is required for: - End users who view Skuid pages - Builders who create and administer Skuid pages