Assuming the hubs are good ones with topics that have lasting power, bringing in lots of views, then, yeah, the traffic should stay high.
You can help ensure that not by writing more, but simply going through your already written hubs and keeping them fresh with new content. SEs like that. Some suggestions are:
- do some editing of stale writing
- update any facts or events that may have changed
- answer unanswered comments and try to encourage new comments
- change photos, make sure they had descriptive text
- look for broken links or update links with better ones and see if you can't improve the anchor text.
There are a lot of hubs here on these topics. Good luck!