The ease with which a competitive product can be coded isn’t the issue. There’s already a bunch of competitors in the field: Webex, Skype and several more. If you want to worry about something, worry about what makes Zoom sticky? What’s their moat?
So far as I can tell, their moat is the same thing that makes them easy to replace, which is ease of implementation (users can self on-board) and ease of use. I have a relatively small position in Zoom and I’ll let it grow organically, I have no plans of adding to it. It’s in my lower confidence group. So long as they keep growing, I’ll hang in there, but it won’t take much for me to exit.