I understand the QRpedia software is freely reusable under the MIT License, today. In other words – people in Brazil or India are able to use the QRpedia technology too, aren't they? And they will always be able to use it whenever they want, without ever having to ask the current rights holders or Wikimedia UK for permission first, correct?

Correct. 

To further clarify - we are not really talking about intellectual property rights. We are talking about the domains currently used to provide the qrpedia service, which are qrpedia.org and qrwp.org.