Yet, feature-wise, nothing comes even remotely close. Nothing Cisco offers (Webex is a trash dumpster fire), Skype for consumers is garbage, Skype for Business marginally better, and the FOSS crowd... Mattermost is a decent Slack alternative but no video calls, Jitsi is flattened against the video call capabilities of Teams and Asterisk can't even get a multi-party video call done. Zoom is video calls only, and appear.in/whereby too (plus Whereby tops out at 12 participants).
Hate to admit it but MS Teams is so far away the others might just call it quits, the only thing it would need to completely ditch Webex and S4B at my employer would be an easy way to invite totally random guests to video conferences and support for dial-in via telephone as fallback.