I don't think that this usage is limited to かと思うと. と思うと probably has plenty of examples.
often this is used when a second, contradicting thought follows.
I don't think that last example is the same usage. What the others have in common are 1. Continuing, every time type occurrence (e.g. When [every time] I think X ...) 2. The result is feeling / emotion related.
The third example is a) Past tense, once off. b) The second half of the sentence /isn't/ the result of the first. c) Isn't かおもうと but かおもったら
Kono joutai ha kono mama da to tsudzuku ka to omou to ochikonde shimau. When i think this situation might continue on like this i get really depressed. What do you guys think about how this sounds? (roomaji de Gomen ne ^^')
I think it doesn't need that "da to" in there hehe
When 'dato' is used, J would be この状態が（このまま）続くのだと思うと、落ち込んでしまう。 ちなみに、type tuduku で つづく、続く