I may be reaching here a bit, but Gilligan and company love to use foreshadowing and I've picked up on 3 things with Kim. First, she was the one handling the vacuum cleaner guys card and had some interest in it until Jimmy turned the page and kinda made her put the card back. Second, her mother's statement "I didn't think you had it in you." And 3rd, Jimmy made a similar statement about Kim not being strong enough to handle what they were about to do to Howard. I still think Kim has something to do with Lalo no longer being a threat and Mike, or maybe the vet, helps her disappear. There is no mention of Kim in BB and Saul thinks Lalo and Nacho are still alive in BB because he thinks Lalo or Nacho sent Walt and Jesse to kill him.
Also in BB, Gus seems to have free reign and really has no worries about his business, like he does in BCS. The only Salamanca he has to worry about is Hector, and he is in the nursing home. Even Tuco doesn't care about or even mention the Chicken Man. He even takes out Don Elido and eliminates all his competition. So something happens to Lalo that Jimmy doesn't know about and same with Kim. I'm guessing Jimmy assumes she is dead, but that Lalo and Nacho are still out there.
Again, we are all guessing. I thought Howard would be so embarrassed and disgraced that he would off himself. Didn't even consider that Lalo would just show up and end Howard without even a thought...just did it. Shocking, but completely in line with Lalo's character.
Lalo and Tuco are two very interesting characters. Tuco was just plain crazy unpredictable, while Lalo is more cold and calculating unpredictable. Both characters are very well written and played.