Pretty much any webapp can be replaced with local desktop app for security and privacy concise people. Some of things I wish had desktop version:

1. CRM - I don't want to store private customer data on 3rd party servers.

2. Budgeting app - Used to use Quicken but it moved to web and I switched to Mint because it is free. I tried some free opensource apps but experience was not smooth. So I am sticking with Mint for now.

3. Trade analysis apps - Sites like TradingView or TraderVue are great but I don't want to put too much effort in there. I rather have my trading data stored locally on my machine. As a programmer, I export CSVs and run them in local Jupyter notebooks but I think a more user friendly version should be high in demand.

On my current team we work on a cashiering desktop app, that needs to interact with local devices for processing checks and credit cards. Although almost everything reaches out to an API at some point, I'd generally say desktop apps are still relevant in cases like this.

Bluetooth PoS printers are a bitch to work with and good luck doing that from JS.

Stuff that needs low-level access to the file system. You can now handle that at a crude level with web form file uploads and generating dynamic data URLs for download, but it's still not as smooth as using the native file system.

Edit: one example would be a file backup system. There's no way you want to make the user manually select and upload every single file on the HD for something like that, and (for obvious reasons) there's no way for a web app to scan the disk and read arbitrary files.

Something that requires absolute real time responsiveness?

There are web-based (in browser) CADs and DAWs... What sort of application would be more demanding?

I am not sure. Something that has a lot of back and forth with peripherals?

Anything that touches a lot of files?

Ok, but what kind of business niche would that be?

You can also touch a lot of files on a webserver, although it would be a pain to upload them.

Sure, a lot of people keep their stuff on somebody else's servers — a.k.a. the cloud — but there are still users who have plenty of local files: music, photos, code...

That's a wide range of users, so I don't have a specific product idea, but seems like some kind of opportunity may exist in this niche.

(If I had a product idea, I'd probably try making it myself — native desktop apps are much more fun to make than web.)

>native desktop apps are much more fun to make than web

This has also been my experience, and I am curious what the reasons are. Does it have to do with the quality of the end result, or the process of development?

For example file management. "Directory opus" is a windows desktop 'better explorer' in this category (I have bought a license myself, it's pretty darn good).