Thanks for the info, I guess this will help get OW status for X'mas 2016 for my wife, here is what I am thinking:
match TK *G to Gulf Air in April this year (2015), which will last 2 years as you stated. Then I will match to Air Berlin Early Dec 2016, in time for X'mas 2016 and potentially be able to use it again for X'mas 2017.
Would be nice to go status-hopping but you never know if they status match anymore in future...