The words of AFGSC commander Gen. Stephen Davis are, in my opinion, clearly a matter of describing the current status of China's bomber capabilities. Not the potential to develop it further, the timeline to develop it further and so on.
Even if H-20 prototype was unveiled to take its maiden tomorrow - and coupled with the mysterious H-X bomber drone - it still takes time to develop capabilities transforming China's bomber capabilities from a regional one to intercontinental one.
We'd be talking several years to finish testing and development, a few years to ramp up production to an acceptable level and even then few more years to accumulate the number of bombers to a useful fleet. We'd still be talking about a smaller fleet than the US one, but the idea is to develop a credible inter-continental round the clock bomber threat. That may be achievable with dozens of intercontinental bombers, not 150.
The H-X bomber drone may help speed up said accumulation though, if two different designs are produced at two different places. Certainly, the design seems large enough to serve as an intercontinental bomber, even if its payload may prove to be fairly modest.
But even then, one needs time to train for a bomber doctrine and said development time can only truly start its execution phase once you have enough bombers to actually do it. So, while that may start as soon as the first unit is being stood up, it'd surely take several years more to be fully fleshed out. So all in all - as said, even if H-20 prototype is unveiled tomorrow - it's doubtful a meaningful force would be available before mid to late 2030s.