PvZ Late/Ultra Late game

  (Edited: )

Hello Guys, before i discibe my problem I want to introduce myself. I'm Granas, a NA and EU Top 25 Master. So I got some Gameknowledge and decent Mechanics (also talked with some GMs about my Problem, but no good answer). There is one Situation I see more and more going to happen and I have no clue what to do if this is going to happen( And i am afraid that this could become a metagame). This is not supposed to be a whine thread and i hope you don't troll this but may help me with this.
The Situation i am talking about is on the late - very lategame. Protoss and Zerg got 3-4-5 Bases. 20 Minutes of an even game Doesn't matter so much what happend before. As i sayed even makro games. And then the Zerg starts with producing mass Swarm Hosts and supporting them with MASS Crawler(Spin or/and Spore), 4-5 Viper, maybe som Infestors and Hydra or Corrupter(saw both styles. I think Corrupter are stronger in this situation because they can go move arround the army(Space) and for example snipe the Mamaship if you try this like Trap today in Code A.

So the Zerg camp behind his Crawlers allways sending his Locusts to you. And they WILL do damage.Even if it's just a bit, it doesn't costs him anything while u lose more and more(while he can bank more and more money). But its like BL/Infestors. The real Problem are not the Broodlord but what is arround them. 

The logic consequence is to build a lot of Kollosi which can be get abducted by Viper. You should be able to kill them with feedback, but the locust are killing your High Templar vey fast because they are high DPS Units vs low LP units and the Range of Feedback and abduct is the same. Storm is no real answer, cause it costs a lot of energy and you can do it just for a short time. Not forever like the Zerg. Same goes for the Idea of Building a lot of Tempests, abduct into mass anti air. Archons dies to easiely vs Swarm Hosts. And you cant outmove your opponent like you could do vs BL/Infestor, since he can also can send Locusts out and move to another position. Its more like he outmoves you. Drops are not an efficent answer you lose to much, doing to less dmg.The real Problem is not that you cant defeat it, but you cant fight it nearly cost effective as he does. And the longer the games continue the more the Zerg will make you starve on Minerals/Gas while he is going to bank more and more money. And you can't crush this army twice(or something he rebuild)

I tryed: mass drops(Zealot, DT, Immortals), different compositions(air, ground/mix) and Base Trades( worse case senario) First possibilty i can think of is an Timing attack as soon as you see the Infestion Pit working while scouting every 1-1.5 Minutes with an Hallu

One typical Player of this style is Root.Catz.So guys the Theorycrafting can starts. What to do? I have no clue. Pls help! (PS: ask for nerves would be cool, but doesn't solve the situation right now^^)