From Blizzard's Warlords of Draenor: Alpha Patch Notes: (Emphasis ours.)

"Automatically Learned Glyphs 

While leveling, characters unlock Glyph slots at several specific levels. However, in order to get glyphs, characters need to visit an Auction House (and potentially pay way more gold than an average character of that level has yet), or know a Scribe from which to request them. To solve this, we've made characters learn some Glyphs automatically as they level. 

All classes now learn some of their Major Glyphs as they level. Recipes for these Glyphs have been removed. 

At level 25, the following Glyphs are automatically learned by characters of the appropriate class: 

Entangling Roots, Fae Silence, Ferocious Bite, Maul, Omens, Cat Form, Liberation, Pathfinding, Frost Nova, Blink, Fortuitous Spheres, Rapid Rolling, Afterlife, Harsh Words, Flash of Light, Alabaster Shield, Dazing Shield, Avenging Wrath, Templar's Verdict, Levitate, Holy Fire, Fade, Deadly Momentum, Stealth, Flame Shock, Thunder, Healing Storm, Healing Wave, Spiritwalker's Grace, Siphon Life, Drain Life, Demon Training, Ember Tap, Long Charge, Victory Rush, Bloodthirst, Gag Order 

At level 50, the following Glyphs are automatically learned by characters of the appropriate class: 

Might of Ursoc, Nature's Grasp, Rebirth, Rejuvenation, Savagery, Mending, Chimera Shot, Black Ice, Polymorph, Spinning Crane Kick, Denounce, Divine Storm, Word of Glory, Reflective Shield, Smite, Mind Blast, Recuperate, Totemic Recall, Fear, Executor 

At level 60, the following Glyphs are automatically learned by characters of the appropriate class: 

Dark Succor, Unholy Command, Death Grip 

At level 75, the following Glyphs are automatically learned by characters of the appropriate class: 

Death and Decay, Dash, Faerie Fire, Healing Touch, Master Shapeshifter, Misdirection, Slow, Frostfire Bolt, Water Elemental, Breath of Fire, Mana Tea, Fists of Fury, Light of Dawn, Final Wrath, Double Jeopardy, Penance, Renew, Dispersion, Ambush, Cheap Shot, Lightning Shield, Eternal Earth, Healthstone, Bull Rush, Enraged Speed, Shield Wall"

I'm not really leaning one way or another on these changes. It seems pretty obvious that Blizzard isn't happy with the glyph prices they are seeing on live realms.

They state that a low level player won't have enough gold to buy glyphs so they'll give them some.

By my rough count there are 86 glyphs listed above to become automatic (read free). If my calculations are correct this equals out to roughly 20% of the glyphs in the disappearing from scribes books.

As for how this effects the economy I honestly believe a large majority of players will simply use the "free" glyphs Blizzard will give them.

This will likely mean that glyph sales for all but the most desirable glyphs will dry up. If that happens glyph sellers can go one of two ways: sell even higher or sell even lower.

Which way they choose to go is likely going to be up to the glyph sellers on each realm/faction.