The Campaigns of Gustavus Adolfus. Part 1: Some background 

+Shades Anachronisto Oh yes they were still useful in pursuit and reconnaissance, but during the battle itself their mobility was rather squandered by the avoidance of direct charges and hand-to-hand fighting.

I came across a tactical study of Gustavus' success in Bevin Alexander's 'How Wars Are Won', he elucidates how better use of otherwise matching technology can allow for an advantage. The use of squares and other deep formations was proven to make infantry far more resilient to cavalry; a deep block of infantry with pikes/bayonetted muskets levelled was proven to be a perfect deterrent to cavalry (and remained so almost until cavalry was taken out of military service) as horses tend o be unwilling to run headlong into what appears to be a solid and pointy mass. Cavalry are effective at running down scattered or nervous troops, but when facing an unmoving block are less so. I have only ever read of one occasion of cavalry breaking a square and that was in the Napoleonic Wars. (The officer that led the charge died, but his horse fell on top of he square, providing an opening for the rest.) The cavalry of the caracole era was weak because, rather than charge at enemy infantry or cavalry, they simply cantered up to the enemy, fired their pistols, and rode off again to reload. A lot of the strength of cavalry is in the charge, and they surrendered that power by acting as skirmishing missile troops. Insofar as the evolution of tactics and weapons in this period I'm afraid I have very little knowledge, I've been trying to find series on it for a while without luck, and haven't much in the way of literature. Sorry I can't be more help!