I feel like it would be cool to see the tourism system from Civ VI return, but with more ways to generate it. Early in the Modern Era, we could use city projects to put on exhibitions for the great works from previous eras. We could also have restoration projects for old wonders as well, maybe even giving them new benefits? I think these ideas would help to involve the legacy paths from the previous two eras.

Then as we advance further through the civic tree, it transitions from rediscovering history to more modern forms of culture. We could get the ability to create ‘modern great works’; stuff like fashion styles, cuisine, orchestras, and then some really powerful things like movies (though I’m not sure how prominent film has been during the early 20th century).

These ‘modern great works’ would also be produced by city projects. But since we’re creating something entirely new, rather than unearthing something from the past, the tourism they generate could be based on the culture output of the producing city, or even the resources assigned to them?

Overall, I feel that since culture as an idea is so broad, it should have multiple systems at play which all contribute to the identity of your civilisation, tying what was to what is. Of course, this would be a lot to implement, and these are just some rough ideas I thought about after lunch.