1C2S was always meant to favour China, no matter which of your scenarios came to pass, of course DXP knew this.
However, the argument about "needing" HK to fail is not proven by your scenarios. After all, Deng modeled Shenzhen SEZ after HK economically. He knew HK had an effective model to build up the economy. HK's issues are not directly related to the governance model, but the entire city's failure to adapt to the changing winds.
I hate to quote myself, but I think it is very relevant to your points. I believe you mentioned it yourself in the past, the need for technical expertise. That's a reason why HK is falling behind, too embroiled in politics. If you were HK'er, and don't care about politics, why would you stay? There are so many opportunities in mainland China.
Too much time in HK Is wasted debating these issues. The anti-mainland groups put up far too much resistance to any projects that bring HK and mainland closer together. Look at the HSR line from HK to GD. It took almost 10 years for only 26km. Protest after protest, dumb issues like mainland officers doing customs clearance on HK side, meanwhile mainland built the line all the way from SZ to Xiamen.
Like you said, there is a need to think strategically and HK did not. You can argue that this is a failure of democracy, but if people were not so poisoned, perhaps the story would be different.
My father was actually among the 2nd group of cadres who formed the management training class (蛇口工业区干部培训班)of the Shekou Industrial Zone Holdings (蛇口工业区) of the China Merchant Group(招商局). He and his comrades works directly under Yuan Geng (袁庚), most of them are in top managerial positions in important Chinese companies today. I am NOT trying to reveal anything. But if you know anything about Shenzhen, you would know what I am talking about. But dude, you don't really know what you're talking.