The Chinese appear to aggressively moving towards some sort of submarine based deterrent according to this report by the Federation of American Scientists.

They have a satellite picture (commercial resolution) of one of the boomers at a dock:

There appears to be significant development at the Yulin naval base to accommodate this, including tunnels and a demagnetization facility.

The reports that the island is very near the edge of the continental shelf, which means that the subs could get into deep water quickly, which is typically where you want a boomer, except, of course for the fact that US boats have been doing deep water for the past 50 years.

If China gets a meaningful SSBN deterrent, it represents a threat to US military power, though it is probably a stabalizing factor, because it prevents a nut like Lynne Cheney from going postal on a nuclear level on them with nuclear weapons.