Yup, Soul Dew is out.
That's going to be a pain for Keldeo, which is now just walled to infinity and back by the Lati twins. However, in rain, +1 Life Orb Keldeo has a good chance—81.64%, to be exact—to 2HKO +0 252/0 Soul Dew Latias with a rain boosted Hydro Pump! That's actually pretty surprising, if to be honest. Soul Dew Latios, on the other hand, is always 2HKOed by the same Keldeo and conditions. While it may not be as useful, as both the Lati twins outspeed Keldeo and have Roost, I think it's a good demonstration of Keldeo's power in rain after a boost.