I dont think they are completely dime a dozen...
but I do think that good 4th line wingers are relatively easy to acquire, same goes for #6 wingers (a #5 winger is trickier... I.E. best winger in the bottom six)... but C's are difficult, and I think a lot of NHL teams make poor judgments on what equates to a good #6-8 winger.
If a team really needed good 4th line wingers there are still UFA's who are good available for example.
I disagree for this season.
You can always find replacement level players in free agency, but you'll have to overpay a marginal player.
The problem is finding affordable bottom six players who are above replacement on a regular basis.
1) older players who are just above replacement level tend to fall off the cliff faster, that is, they have little margin for error, so you have to constantly replace them - Read is a good example, top six for a couple years, bottom six for a couple years, then marginal by 28 or so.
2) players with some talent become too expensive once they demonstrate that talent, they are either promoted, traded or allowed to leave
What Hextall has done is increase the supply of second tier prospects, a lot of teams devalue later picks because you miss on most and rarely find a first tier (top 6/top 4) talent.
While Hextall has increased the supply of top tier talent by garnering extra 1st and 2nd rd picks (and hitting on a couple longshots in Myers and Lindblom), he is also stockpiling second tier talents - he values later round picks, both in tersm of hoarding them and putting the resources into scouting lesser prospects and developing them.
Twarnyski is a good example, it's unlikely he'll ever be a top 6 wing, but he has size, above average speed, has shown a scoring touch, and has the potential to be an above average bottom six winger. Bunnaman may move to LW and become a 2nd tier PF. Vorobyev could be an exceptional bottom six C. And so on.
Now guys like Farabee and O'Brien and Ratcliffe may start in the bottom six due to a numbers crunch, but they'll be up or out in 3 years because they're too talented to stay in that role as they approach their peak years. It will be the steady supply of 2nd tier players that hold the potential to keep this roster one of the deepest in the NHL for an indefinite period.