Mysterious, inaccessible arena in Elden Ring, PvP DLC?

It's of course about exploring, Elden Ring. To experience and discover at your own pace the myriad of strange places and creatures that populate the sad world. But of course it is also about finding out what comes next (and for some also about crossing boundaries that the developer set).

Northeast of the game's launch area, for example, is a large building that no one has entered. It looks like a Roman arena, a colosseum, with a single miserable figure in front who only says the cryptic:

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All I wanted was to fight. To fight, as a warrior, at last. So why? Why, O guidance of grace, will this door not open?

Lance McDonald have managed to record a video from inside the building (which no one should be able to enter). Thanks to this, many have come to the conclusion that this is an area to be accessible via a DLC, AND that it should have PvP functions. Makes sense, really.

What are your thoughts?