The standalone product's engine won't satisfy players. People who have come to BI's engine thanks to DayZ probably expect some huge improvements to the engine for the standalone, but they don't realise that when BI say they're going to make improvements it's all very understated.
If it's lucky it'll feature ported features from VBS, but that's about it. BI have supported their products wonderfully over the years. The problem is most of that support is band aiding and tiny incremental improvements of the dated engine.
They need to throw out all of the code related to animation and player movement and start over. Keep the player's view attached to the head, independent of the gun (unlike every other FPS) but quit relying on the peculiar movement system where animations cannot be paused once they're initiated. Will BI discard something that has been present in their engine since the late 1990s? No. By now it's probably reams of uncommented mess that no one could even begin to unravel or correct.