28th, to be precise. http://www.bit-tech.net/news/gaming/2015/10/26/batman-arkham-knight-re-release/1
It's been available for less than that steam sale. At one point the complete edition with all dlc was under £8.
I would imagine when it re-released, it'll be around £30-40. so I would guess come steam sale time it'll be around £15ish. Alternatively you can get it from G2A for around £12, of course G2A is tad bit riskier than steam, but in this case i'd take that risk.
G2A have had keys deactivated by Valve or by Publishers on a few occasions now. They don't buy the keys themselves, but allow re-sellers who source their keys from 'legitimate sources' to re-sell via the website. Needless to say some of those re-sellers have made their purchases with stolen credit cards, or bought keys from one region and sold them in another. In both cases when it gets found out those keys tend to get revoked and you're out of a game. In their defense G2A offers refunds when it happens.
Pretty much that. I've used them a few times with no issues, but the games I bought were all pretty cheap. When it comes to more expensive games, triple A titles and the such, I'd probably stick with steam/GOG.
Yeah, avoid newly released AAA games like the plague from G2A. If a publisher smells a rat, they will go after the 'legitimately sourced' keys like a dog chasing it's own tail. If you want a new release that bad, to be on the safe side, you'll need to pay. Either that, or give it 6 months and it'll either appear in a Steam Sale, or on G2A for even less.
I didn't know that. Not that I've bought anything from them before anyway, but good to know all the same...