No. Cuellar is very much favored (Likely D), but you can’t rule out another, possibly even more severe 2020-style D collapse in that region — I don’t think that would require a 2008-style national environment, actually. The lesson to be learned from 2022 was not "trends here have stalled" but "midterms & off-years have their own dynamics, especially in the post-Trump era."
Recency bias is one hell of a trap, as Republicans (emboldened by their 2020 overperformance & VA/NJ 2021 & quick to forget about the 2021 GA runoffs, CA recall, etc.) had to learn the hard way in 2022. Democrats shouldn’t make the same mistake and assume 2024 will play out like 2022 everywhere.
Cuellar's biggest advantage is the underwhelming GOP field, but if things get really bad for Biden, he could still lose in an upset. It would be one of the last seats to fall, though.
Ye, I'll pretty much second this.
The only thing I will say though is that Cueller's seat is basically half based in greater San Antonio that has different dynamics than RGV. This was the reason in 2020, TX-28 swung slightly less to the right compared to TX-15 and TX-34. I could see a scenario where RGV swings hard right again, but crossover support and maintaining margins in San Antonio is able to save Cueller.