The "plan" (a ho ho ho) is that the J will live on until about 2022 with the Mk5s and the last few Ks going when the A400 eventually appears. The J fleet is however colossally f**ked and has been for a while. I get the impression that despite the best efforts of those involved with it on a daily basis AIR and the MoD are rather hoping it will just limp on quietly, with minimum investment, until the A400 arrives and "saves the day".
Without wishing to get all parochial and "Changi slip" about it i still think there will be ongoing niche roles for which the A400 will be unsuitable and for which the retention of a small fleet of C130s would be the sensible course of action. I say that not as a dyed-in-the-wool Herc person but as someone who had, until recently, been rather hoping to get onto the A400 Initial Cadre.