Lia not participating in the world tour means the effective end of her as far as KPop is concerned.
After her, the last notable vocalist of the 4th Gen is Lily M of NMixx, but that is because she had been selected as a vocalist to begin with.
Them, and aespa's Ningning, are among the last of vocalists in the 4th gen GG.
Vocalists already disappeared among 4Gen Boy Groups since they don't do well in the digitals anyways and emphasize performance more.
Vocals are , ahem, like pitchers having to hit in baseball.
In the old days pitchers did not have to specialize in pitching so they could serve as hitters, but as pitching got more sophisticated, pitchers had to concentrate in pitching and had little time for hitting practice.
So the pitcher's time at bat was mostly a wasted spot, but the purists, always scourge on anywhere, resisted so it got worse until in 1971 American League introduced designated hitters, ending the need of having pitchers at bat.
National League continued to hold the old rule until 2022.
If the pitcher wanted to hit the pitcher could be put into the bat, but since only one person, Ohtani Shohei, qualified for it it is more like a special rule. In essence pitchers were no longer part of the offensive. Japan's Central League still holds that rule (and tends to be whipped by Pacific League, who has designated hitters) . Korea always had designated hitter rules.
In KPop acts, the need to put vocalists in occurred because of the probably unnecessary obsession on digitals. that, plus the introduction of IU to attack everyone in the digitals, extended the life of vocalists in kpop by almost 15 yeqrs.
Vocalists , I have to say, are big burden to groups. Since better vocalists are rare specimen, they tend to have more 'challenging' visuals. Except in some cases, a quick look of a group easily showed who was the vocalist. Usually the most visually 'challenging' member is the vocalist, who was selected entirely for the vocal ability.
In addition, like Lia's case, the vocalist is usually the worst dancer, since the vocalist only trained for vocals and didn't really practice dancing.
That limited the dancing performance of many groups, who could not do more challenging routines which the vocalist could NOT manage.
Given that today's KPop is more about perf than vocals, they learned that having vocalists is a huge burden which yields little benefit since the Korean digital market is not as important as it used to be. It is better to put someone of a middling vocal ability who can dance well and train the person somewhat to serve as the 'vocalist', than make someone with good vocals but poor dancing skills and make the team limited to that person.
In the old days, Jung Eunji , who was added to APink at the last minute, was often criticized for her lack of dancing skills. She made it up in other ways but people like her would NOT be selected now. She was only selected because the producer of APink at that time saw IU, again the source of about 99% of all problems in KPop, getting big and thought it was going to be the era of vocals and put Jung Eunji, whose average looks and lack of dancing skills would have precluded her from becoming a girl group member if IU did not stir the pot, to the group at the last minute.
Lia , and NIngning (who is not even Korean) and Lily M (again she is not Korean), are among the dying breed of vocalists in KPop. It is kind of good to see vocalists going the way of Dodo, since they really subtracted a lot from KPop's advance to the world by having to sing songs palatable to the Koreans, not the global fans.
