Should be the full back in the final even if Webb is fit IMO.

If you watch today Mcguire was taking the "role" you describe especially for Halls 2nd try.
With Webby leaving i agree Zac should retain the shirt and maybe we adjust the areas where Webby was most effective but i will also say this year BW has butchered the "perfect pass for the outside man" just as many times if not more than he's created.
Even with Zac at FB i have to say i still think unless its real quality then we can/should be looking from within the u20's first and foremost for a LC and i'd give Keinhorst a go at some point.

Hardaker is not less of an attacking threat than Webb, he's just a different one.

Keinhorst IMO shouldn't be shoe-horned in at left centre. He's still relatively new to the game of rugby league at Under 20 level, and should be allowed to learn his trade on the right hand side where he's played all his rugby so far. Promoting him to first team and asking him to play in an unfamiliar position would be a real challenge for him.

A year out on loan or dual reg somewhere next year, then see where he is in his development.

AG-Keinhorst has played quite a bit in the LC role for the u20's so i don't know where yer getting that from.
Admittedly he did seem to roam and play both sides in the 9's but i can asure you i've seen him line up at LC more than once.
Also i'm not saying shoe horn him in there just give the lad a go in a couple of games (2 out of the last 4 SL games would of been ideal) just to see where he is development wise he's clearly more than comfortable at u20.
Plus imo unless it's real quality i don't see the point in bringing in an outside recruit.

great performance from Zak imense under the high ball good returns and always a threat.

He doesn't have to though does he. A fullback doesn't necessarily have to be an extra halfback, that's just how it's been for us for the last few years because we've had Webb in our side. Hardaker is his own man, he doesn't have to fit into some pre-conceived model of how a fullback should be. We'll have to adapt our style to play without Webb now. At least we won't get pulled for the inevitable forward pass every few sets.