Most upvoted comment
Amazon Digital Holiday Sale Has Arrived! $2 Aliens: Colonial Marines, $19.99 Metal Gear Solid Revengence, $14.99 Firaxis Pack (Civ V Gold, XCom EU, Civ IV Complete) + hundreds of deals.(r/GameDeals)
Tomb Raider at $7.99 is the lowest I’ve seen it–ignoring free with an AMD video card. Though it looks like the regular price has finally come down from $49.99 to $19.99. Assuming other stores follow suit, it’s possible it could go lower than 60% off.
Edit: The Amazon sale wiki says it’ll be $4.99 Dec 24-26.
Don’t know if the forthcoming Xbox One/PS4 Definitive Edition would result in some new version or bundle on the PC side in the next few months. According to this, it seems possible, but not currently planned.