Subroc type of Anti-Sub missiles would be carried in the VLS.
054 series has a passive towed array in the back... which is the primary ASW sensor.
VDS is good for shallow waters, and when you go active.
there are advocates to put a new VDS, or even a U (underwater) AV back into 054 follow-ons.
There is no reason that an ASROC type of anti-submarine missiles can't be carried in a non-VLS launcher. If they don't have space for a VLS that launches both AShM and ASROC, they could certainly launch them from standard launcher. The problem is that even though the PLAN mentioned that 054A has this, we have not actually seen any picture to proof it. He also said at the time that 054A was using TAS and we didn't have a proof of that either, but now we do.
The reason you have TAS at the back is because the back of the ship is normally the noisiest part of the ship due to the propulsion unit and the sonar located at the back would have to be at a distance away from that noise to be able to detect anything. TAS is very important to detect submarines or other ships that are behind it. If the ship wants to detect objects at the other directions , it still needs capable hull mounted sonar. And having a large powerful bow mounted sonar is very important. Why do you think the Virginia class submarines have such a huge spherical bow mounted sonar + chin mounted sonar + flank array sonar? You seem to follow the Chinese bbs misconception that having TAS on ship is equivalent to AESA radar on fighter jet.
btw, I think you are referring to UUVs there. UUVs are more important for MCM missions than ASW missions.
As for VDS vs TAS, they obviously are more effective vs different types of targets. You equip whichever one based on your requirements.
It costs about 405 million USD to refit and reactivate Iowa battleship in 1980s, and that is less than the cost of one oliver hazard perry class frigate. The type 054As should cost much more than that.
Are you comparing the cost of unionized workers in America to cheap labour in China? You do realize that China has the most efficient shipbuilding sector in the world, right? 1.58 billion RMB is the cost it was quoted to cost per 054A when it first came out. Now, that probably doesn't include the weapon development cost or the cost for designing the 054 series of frigates. But considering how many they are building, that cost would be spread out and be pretty cheap. And once you are mass producing something like 054A, the cost just gets brought down.
F-22P and 054A are totally different beast, wouldn't you know that. Cost of my car is also only $30K, why can't China sell 054A for $30K ?
It's hard to believe, but China actually made quite a bit of money on the F-22P deal. F-22P deal is just an indication of how cheaply Chinese shipbuilding sector can crank out warships.