Well there were many very tight-knit formations in previews TW games, with the Phalanx on the high end. I personally would like to see some ability for lineformations to reduce casualities from ranged fire. There is plenty of evidence for example that many went down to ground to protect themselves from cannonery. Lay down! would be a nice order.

I really hope that skirmishers can make the best use of trenches, hedges and every natural obstacle to increase their protection. A very spread out "line" is a must for me.