The Wyrmrest Community Project is indeed still around and quite active. You can find their forum post, and an invite to the server, here.
Originally, they focused on Alliance and neutral RP. They started allowing Horde events to be posted a few months ago, but there are many Alliance and neutral events on their calendar, and they have an LFRP channel for finding other people for random/semi-planned RP. Additionally, they’ll be running an Alliance guild faire in Stormwind next month; you can find details in the discord or in the event’s forum post here.
There is Alliance walk-up to be found, but it’s moved from Stormwind to Duskwood. I don’t know how early in the evening people tend to start congregating there, but you can ask in the WCP discord or in Thomas Bates’s Duskwood Thread.