Amusing how books have to achieve a certain vintage before names from them become acceptable. I wonder if, in the year 3000, it will be acceptable to name a child Arwen and not have it thought of as weird. Or perhaps there needs to arise a cult around LoTR before that becomes acceptable. If Scientology enters the mainstream, perhaps children will be called Xenu completely normally. Maybe the name Jesus will be treated like the name Nimrod.
Then again, there is powerful normalcy-bias here. A name is acceptable if it is very similar to established names and if there is variance it's rarely among the established power class. So perhaps we'll need a massive disruption. The Scientologists will have to kill a large number of people and subjugate us to have names no longer just be James and Jennifer.
Or maybe we'll need a modern well-loved person to call their child Eliohann.
I met a lady named "Arwen" once. I asked her about it and she just said "My parents were total LoTR hippies." But while it stood out to me at the time, it didn't strike me as name that was ridiculous or anything. Just distinctive.
Now Frodo... that would just seem weird. Or Gandalf for that matter.