I believe both "Watchtower" and "Jehovah's Witnesses" will fade away and "JW.Org" will be the official moniker of the WT.
I can't help but think of "Kentucky Fried Chicken", now known as "KFC".
Ask anyone under the age of, oh, 20, about "Kentucky Fried Chicken" and you'll likely get only a blank stare. They all know it solely as "KFC".
In the year 2040 or 2050, no one will remember "Watchtower" or "Jehovah's Witnesses". It will all be "JW".