I don't think that it's an exaggeration to say that the only reason YGE is still considered a major label is because of Blackpink. The lion's share of its revenue is generated by just one extremely profitable group. Even in terms of legacy acts it's not looking great with BigBang members leaving one by one.
And just to clarify: YGE is still doing more than fine. Treasure while not as big or popular as some of their peers have a decent sized fanbase and they've been quite successful at touring. They remind me of their seniors: iKON and Winner (just with less domestic hits). And as long as they consistently tour, they will still be a positive asset for the company. What people might not know is that YG Plus, an YGE subsidiary, is the main distributor of HYBE - meaning that the more albums groups like Seventeen, TXT, Le SSerafim, NewJeans sell, the more profit YGE gets. So this is not a doompost about YGE going bankrupt or whatever. But if Blackpink doesn't re-sign, YGE will be a CUBE level company, not a Big 4 level one.
Either way Babymonster is their first girl group in 7 years and more importantly by all indication the members are the best of their talent pool - I don't think they will have resources or trainees to debut another girl group in the foreseeable future (especially if the rumors are true about TBL gg). Treasure and Babymonster will be the only "results" of YGE's entire 4th generation. If BM ends up with NMIXX's level of success - in my opinion it should be counted as the company's failure. Especially compared to other Big 4 labels: Stray Kids, ITZY, Nmixx for JYPE, Aespa + some of NCT for SME and a ton of sucessful HYBE groups.
For what it's worth I think Babymonster will do really well. This subreddit doesn't like YGE groups very much, but there has been a ton of hype around BM despite the lengthy pre-debut cycle. They get more views on YouTube and TikTok than most active promoting groups, and obviously they'll get a ton of support from the blinks as well. It's just that for me personally the expectations are set quite high in terms of success. I think if they don't become as big as let's say Le Sserafim or IVE, it will mean that YGE is no longer being able to produce top tier groups. The company will literally be Blackpink plus friends (if they decide to re-sign).
TLDR: if YGE's entire output in Gen 4 is one boy group and one girl group, neither of which are top-5 in their generation, it means that they no longer compete with other Big 4 labels. Babymonster will be the litmus test on if they still deserve the reputation and status they have as a company.