> Starting with Qt 5.15, long term support (LTS) will only be available to commercial customers. This means open-source users will receive patch-level releases of 5.15 until the next minor release will become available. This means that we will handle Qt 5.15 in the same way as e.g. 5.13 or 5.14 for open source users.
Or, in more words as Qt pusts it:
> Starting with Qt 5.15, long term support (LTS) will only be available to commercial customers. This means open-source users will receive patch-level releases of 5.15 until the next minor release will become available. This means that we will handle Qt 5.15 in the same way as e.g. 5.13 or 5.14 for open source users.
It has nothing to do whether mirrors do exist or not, when there will be nothing to mirror.