Quote: "
Incidentally, R3 is planned to operate permanently in mixed mode from the outset, serving both T6 arrivals and departures."
Yes, it would have to, until such time as a fourth rwy was built.
AFAIK, they estimate 702,000 annual movements with 3 rwys, that's a fairly significant extra 222,000. Whether it's enough in the long term is anyone's guess, if not, start planning the 4th rwy now.