No one - and I mean no one, including Disney brass - expected TLJ to match TFA's gross. That's not how the movie business works. TFA was the result of 10 years of pent up demand and unparalleled fanfare. No one, I repeat no one, expects TLJ to match TFA's gross.
And if you think producing a movie that makes a billion dollars in two weeks gets you a target on your back, you are again profoundly mistaken.
There is some truth to that, of course - but it is also a lot more complicated than that.
They spent far more making/marketing TLJ than they did TFA. Industry estimates are that TLJ needed to hit $800M to just break even. It's sort of like Pirates - yes, they still make megabucks in terms of grosses comparatively to other films, but they keep spending more and more on them, as well. So the profits are shrinking from both ends. You just need to look at how heavily they marketed TLJ to see how much more they spent with TFA, which, as your other post pointed out, pretty much promoted itself.
At the same time, they also pulled back some of the merchandising (the other main source of income) because the toys/etc. aren't selling as well as they expected for various reasons - one, kids aren't the main audience for action figures/etc. any more, and two, the adults that are just are not as interested in buying up every last new character they show for five seconds in the film like they were for the OT (where the biggest demand is for "that random Jabba's guard who showed up in the back of the skiff behind Luke in ROTJ that didn't have any lines).
They aren't even rushing out to buy all the main characters - there are still dusty Finn's and Poe's sitting on shelves leftover from TFA next to the new TLJ stuff. Kylo, Rey, and Phasma are still selling well - but folks aren't caring much past them. That's why Hasbro is bringing back The Vintage Collection this year - the new films have not been the merchandising bonanza that they hoped, so by bringing back the numbered figure collection, they are trying to entice those "got to have the whole series" and picking up a toy line they ended before TFA came out (and continuing the number sequence from where it left off before some of the young kids they were aiming for were even born).
In any case, it is really the Solo film that is going to be the real test of leadership. And while it may end up being a smashing success, it's not looking particularly good right now. At least, Disney isn't showing much confidence in it. The film comes out in five months, and it doesn't even have a trailer yet - or even an official poster (the one that made the rounds over the past week or two was a fake). And no matter how you cut it, it's difficult to find such a high profile film in a franchise that could be more objectively called "troubled" - even if you go past the rumors (that the main actor was so terrible they had coaches standing next to him the entire time like he was a child actor and needed constant work).
The fact that they fired the directors so deep into production and had to bring in someone like Howard to do the film is just unheard of at something of this level. (And before someone says "Justice League" - that was not because of creative differences, the director lost a child rather tragically and left - totally different situation.) Sure, directors come and go during pre-production, but this was just huge to happen after so much of the film had already been shot. For Disney/Lucasfilm to decide to part due to "creative differences" at that point shows an utter lack of management skill on Disney's part. The budget ballooned because of all that, so it was unquestionably a major blow - and with the utter lack of a marketing campaign so far, it really looks like Disney just doesn't want to dump any more money into it then they absolutely have to at this point. Either that, or they were waiting to see how TLJ fared and are just waiting to delay it - it will be interesting to see if they just pull the band-aid off as quickly as possible and just get it out there and over with, or if they indeed do delay it until winter.
If anything is going to cause a shakeup at Lucasfilm with Kennedy, it's going to be Solo. The timing and idea itself just appear so tragically miscalculated at this point. Recasting one of the very most unquestionably iconic roles in Star Wars, in fact, one of the most iconic roles in cinema, so soon after killing him off. The choice of running it so closely behind TLJ. The actor they chose, who is nothing like the original in looks, stature, or if rumor holds, skill. The whole thing just seems like a terrible idea pushed by marketing folks who said "Han Solo trends really high!" They really should have done the Obi-wan film first.