If LTC was at $4 today and you turned the machine on, you would likely not ROI until July 2017 (LTC baseline). That assumes the same stability of difficulty we've enjoyed for the last year. With a flood of new A4s, difficulty will jump up across all coins so it'll be interesting. I'm assuming the base unit is $1800, $150 shipping, and $200 for a EVGA 1300 PSU with power at $0.10 with an average difficulty increase of 0.1%. I would call this the BEST case scenario.
Shipping should be a little less than $100 per earlier posts.
Power at 10c/KWH is HIGH for most miners, "best case" would be more like *3* (and for me currently 4.5 but hopefully under 3 sometime next year).
On the other hand, I DO expect the network hashrate to about double over the next year, possibly a little sooner - depends on how fast they can get units built and shipped, and on their chip supply (Bitmain has had OBVIOUS limits on how many chips to make S9s they could get at a time).
One up side of the delays - my A2s have managed ROI. 8-)