BranjoHello: With this release happening soon I hope what first one of the series finally gets bundled with all the DLCs and available for a reasonable price.
Knowing that such thing still hasn't happened for Rome 2 (which is even older game), I'm not holding my breath too much.
If you're waiting for this then I'm sorry to say I'm pretty sure it's not going to happen. The reason is that the best part of TW:WH2 is the Mortal Empires map, to the point that once you have it you have no real reason to play the inferior vortex campaign.
I was waiting for TW1 to be cheaper than £10 base game for a while because I was assuming, as you are, that over time such sales will get cheaper. The base game and DLC for TW:WH1 is the only way to play the other races in TW:WH2 (with the exception of some WH2 DLC for the wood elves just recently). This means that the DLC and base game is not going to devalue, it's as relevant for TW3 as it is for TW1. All the races for TW3 will be new, so they've no reason to reduce the price of previous dlc (in fact they'd be canibalising sales of the new DLC, business sense suggests they should keep it more expensive).