SLBMs are good if you attack first but bad if your opponent does, which is why both SLBMs and ICBMs are needed.
I don't understand this - SLBMs are the most survivable form of nuclear deterrent basing there is. Their greatest advantage is second strike capability.
At the moment. That could change any day and when (not if) it does it won't be gradual. Once they can be detected they may as well be sitting at the pier for all their survivability.
Even if an SSBN was broadcasting its position constantly, sinking a submarine at depth several thousand miles off your coast is still a challenge for PLAN. They deployed their first MPAs what, two years ago? They have all of six SSNs, that presumably would be at least as vulnerable to any massive technology change that made the oceans invisible. An SSBN is still a moving platform under water, which is a lot more challenging then anything sitting at a pier.
Again, not advocating for ICBM removal, I just think people are being a little hyperbolic about SSBN vulnerability.