And henceforth no competitor to the USB-IF will be allowed?
Not necessarily. A new connector/standard would require the backing of industry and companies to even just get off the ground. Its just like the HD DVD/Bluray battle. Companies took a side and eventually the market chose a winner.
If someone comes up with a new connector and specification that rivals USB, it would need support from relevant industries/companies and prove itself in the market. Put another way, for as long as companies place their support behind USB, then it’s very unlikely that a rival would come along.
For now, the USB specification (not just the connector) is so entrenched that this scenario is unlikely. What’s more likely to happen is maybe a new connector that the USB-IF comes up with that improves on USB-C. Although for now, USB-C serves its purpose well enough that even Intel’s Thunderbolt also uses the connector for their specification.