I think if they're going to retire the DDGs and replace it with 052DL, it's going to be the OG 052 first, then 051C (because it's steam-powered and refitting S-300 is going to be costly). The MLUed 051B, 052B, and Sovremenny can stay a while longer or get demoted into "super frigate" category
112, 113, 115 and 116 will be replaced by 055 with the same pennants.
101 to 116 will be 055. Question is 117, 118, and 119 will remain 052D or will they have their pennants changed (127, 128, 129), so that 117, 118 and 119 will be given to 055. PLAN is known to change pennants when it is inconvenient.
The MLU destroyers will stay a while longer but eventually get replaced by 052x, when their turn comes and after the remaining pennants run out. For example 160 and 166 will arrive first before 167 will be retired and pennant transferred to a new 052x. Then 168 and finally 169.
I think that retiring the old destroyers will be appropriate as they might cost more to operate than a 054B while having less capability and less comfortable for the crew.
At the end assuming 117 to 119 are transferred to 127 to 129, 120 to 139 will be all 052x, then 150 to 179. 140 to 149, 180 to 199 will remain reserved for another type of destroyer.
I am also suspecting that 052DL itself might be superceded by a further improved 052D batch, perhaps with another radar alteration. At one point we may also see the MLU of the 052C.