The rumor is that Elden Ring has 10+ DLCs on the way (or updates, if you prefer...I'm guessing some of them will be full-featured expansion pack type paid DLCs and I hope one of those is out soon.
The arena update was "DLC 01" internally at From, and the extra digit there indicates that they plan more than 10.
Rumor is DLC 02 will be a boss rush mode that lets you set the parameters / choose boss fights and go through a bunch of them in a chain.
I could see this game getting major updates 2-3 times a year for the next four years or so. I wasn't sure how I felt about games getting continually updated like this, but lately I'm starting to like it. Dragonball Z Kakarot just got its fourth paid DLC and they announced a 5th and 6th on the way over the next year-ish. And the DLCs for that (well, 3 out of 4 of them) have been pretty high quality for the price. AEW Fight Forever is going to have a DLC update model instead of sequels like the WWE '22 series. Seems like this is becoming more and more the norm and I'm not against it. Would have been awesome if we'd had things like this when I was a kid, like if Chrono Trigger or Super Metroid kept getting updates or tweaks. Imagine A Link to the Past getting a new dungeon/overworld area added to it like two years later or something.