There is room for niche stuff, but this blog post is too vague to determine what niche they are now trying to fill.
As a previous coda user and someone whose spent a considerable amount of time with many IDEs/text editors, it looks like they forked vscode and are trying to see if people want them to develop a new app.
If they are actually using something internally that was good, then, as a development software selling company, they would be promoting the product’s actual benefits instead of writing this fluff about considering/reluctantly releasing their ‘awesome internal tool’. How many companies make their own internal editors anyway?
I'd also like it to use iCloud for sync. Panic explained a little bit about why it uses its own platform in a blog post I found recently, but it was kind of vague.