I watched it so you don't have to. But, eh, I don't see a clear stance really. On one hand the person says Chinese navy has pretty much reached the point where additional new destroyers aren't needed. But then later on, he says when a new generation of ships is ready, that the dumplings will continue.
Of course, we're talking about a random Youtuber, so his opinion is not necessarily really worth more than yours or mine on this forum.
It is true, however, that pretty much all the destroyers PLAN has are either newly build or have been modernized in the last 10 years. So, I don't see large scale retirements in the coming few years. Any additional destroyers would have to come on top of everything else. Increasing personnel numbers and requirements.
Just how much room is there to increase personnel is next to impossible to say. We seem to be seeing those 056 corvettes being replaced with additional 054A frigates. That in itself will require a pretty big jump in personnel. Carriers are a whole new class - each new carrier will require even more additional personnel. Not sure about landing ships - but if the older ones don't get retired in big numbers, then new 071 and 075/076 will also require additional personnel being recruited.
Same will likely be true for nuke sub crews. I don't see those replacing the old conventional subs, personnel numbers wise. It's more likely the overall number of submarine crews will shoot up in the coming years.
Just where the limit is in PLAN's requirements - how many sailors does it plan to enlist? Who knows. But such a figure could be key in answering just how many more new ships will we see in coming years.