"better than the poster Jim Carroll calling it trolling? "
I have put my argument as to why don't believe modern songs can become pop songs - you have responded with personal insults, ageist attacks on the people who were generous enough to pass on their songs to us and without whom we would have had nothing to sing, and with an attitude which sums up as 'they can because I say they can' not unsimilar to 'a song is a folk song because I choose to call it a folk song' - not very convincing, I'm afraid.
Some popular songs have become traditional in the past because the process that made it possible, an active, creative and recreated oral tradition, was still in working order - that is no longer the case.
Modern songs come out fully formed and with the owners stamp clearly displayed on their behinds - they can never belong to 'the folk' - they will always belong to the owner.
Any passage through any oral tradition that may remain is controlled by that ownership - by law.
The only chance of them becoming traditional is if they are parodied - happened a lot in Liverpool where I grew up
One parody I remember took a hit song of the time 'That's Amore' and made it:

"When your boil suppurates and it runs on your plate, salmonella"

Don't know if it ever got any further than the Liverpool Docklands - but it had left home and become something else.
People have argued that 'You'll Never Walk Alone' has become traditional - don't agree - the tradition is far more complicated and creative than simple repetition - it involves, creation, re-creation, passing on, recreation again and passing on again - ad infinitum, and in each place that happens, those involved claim it as their own.
We have been staggered over the last forty years while recording in rural Ireland and Irish Travellers in London by how many songs we found that possibly originated in Scotland or England, yet which the singers insisted were "Clare songs" or "Travellers' songs", or "Irish songs" - or even "Miltown Malbay songs" - that is a sign that a song is part of an oral tradition.
We were recording a 95 year old singer last year (sorry guest, it wasn't his fault he was old) here in Clare - he gave us 'Catherine Jaffrey', 'The Keach in the Creel', Lord Bateman', 'Lord Lovell', 'The Suffolk Miracle' and 'The Girl With the Box on her Head' "all good Irish songs"!
On top of these imports and the hundreds of Irish-made songs we recorded, we have discovered a tradition we were totally unaware of, of local songs made during the lifetimes of the singers, reflecting local happenings, big and small, from protests over land distribution, local Fairs, The West Clare Railway, an ambush of Black and Tans leading to the destruction of three towns, a shipwreck.... down to a local man going out on a bender and getting barred out of all the pubs.
All of these songs are anonymous, and the people we asked, if they hadn't heard them they remember the events.
As our old singer said, "in them days, if a feller farted in church, somebody made a song about it".
That is a tradition in action, now, alas gone.
The fact that some people might choose to use the terms 'traditional" and "folk" because it gives the songs that happen to like some sort of status or title, doesn't make that use a valid definition.
Similarly, if a mass of people misuse the term out of ignorance because that are not involved in the music, we don't take on those misuses and manipulated definitions as valid until they are taken up by enough people to have become identifiable, agreed upon definitions in themselves - a quantum physicist, or a botanist, or an electrician... whoever, goes on what they know and have learned, not on what somebody else doesn't know and is not interested in.
The problem with all these discussions is that any attempt to arrive at an agreement is looked on as a criticism of somebody else's musical tastes - it isn't, and it never should be.   
As far as I'm concerned, it is an attempt to create a situation in which we can discuss our interests in folk music in a friendly and helpful manner so that we can pass on what we think we know and benefit from the knowledge of others on a forum that describes itself as being about"Traditional Music and Folklore Collection and Community" without nastiness and abuse -   
It seems to me a crying ***** shame that we can't "what is a folksong" has become as taboo as sleeping with your sister.
Jim Carroll