This is absolutely NOT a concern.
Even if I had every DoH and DoL class maxed out I would still buy the majority of my gear. I'm sorry, but when I'm logging on each day enjoying doing end game content (raids, NMs and such) I am not going to want to spend my evening play time mining ores, havesting grass, cutting wood, crafting lumber, farming hides, tanning leather, refining nuggets and ingots, weaving cloth, pounding out sheets of metal, wire, rings, cutting straps, forging buckles and grips, pounding out blades and lids, and.... the list goes on and on and on.
I'm just going to search for the items I need, and buy them and get back to playing the game. There will always be LOTs of players with this attitude.
It might not be a concern for you, but I'm sure 95% of people who will spend hundred of hours leveling DoH classes WILL want to put them to use. I think you're in the minority here. Any serious crafter will have gathered large stocks of the common crafting components, making putting together gear very easy. And it only highlights another problem. There's WAY too much gil in the game right now. People have been amassing together fortunes for nearly 5 months now, with nothing at all to spend it on and remove it from the economy. It's hard to predict what will happen to the market, tons of supplies offered, but so much gil available to be spent, the prices might go up regardless of supply/demand. And since all that gil is essentially just shifting hands right now, it'll be tough to stabilize till gil is taken out of the economy.
That didn't really come out right, it was mostly in answer to elevencharle's claim about it balancing out and deterring people from leveling too many DoH classes, making it sound like its a good thing. I don't think Physical Level is much of an issue though, it will level up faster than your classes regardless of which path you take because of the need to level multiple classes. I have nothing against people choosing to level DoW/M exclusively. I just think picking up a new game and seeing half the classes are saturated to the point of making them useless is a bit of a turn off for a new player. From my understanding leves are already how most people make the most of their money anyway.
FFXI - Bruknar - WAR75 MNK75 BLM75 NIN75 SAM75 WHM75 DRK75 BRD75 RNG75
FFXIV - Bruknar Dinendal - Istory.