I'd kind of prefer a selvedge fabric - between the interior placket and gusset, the workshirt does a really good job featuring the selvedge line - which IIRC the super heavy chambray isn't. A heavyweight selvedge chambray could be pretty cool, though, particularly if it's more interesting that just the indigo warp / white weft fabric.
Maybe @joshgustin can list out a couple of fabrics that could potentially be used in a workshirt campaign, then there could be a polling thread here or on reddit. I imagine there would have to be a minimum number of votes for the winner in order for a campaign to be launched.
Alternatively, I supposed Gustin could just launch a campaign with at least 100 units required for full backing (maybe add a few extra in case of cancellations) and just not place the order if there aren't enough backers.