I would I like to ask the same questions of middle school teams as Trent_C just asked about high school teams.
The questions were:
1- based on what you have seen, what percentage of teams do you think will be able to score cubes, skyrise, or both at worlds? (I ask because I want to know the importance of getting a skyrise claw and skyrise auton by worlds)
2- if your team was ranked in the top 8, what kind of robot would you select? Cube, skyrise, hybrid, one with a good auton, etc.
At this stage of the game, with Worlds being only a week away, my own advice is to stick with the design you have and make it work as well as you can. Make sure you have plenty of practice driving the robot. If you have an autonomous, make sure it’s reliable and consistent. Inspect your robot very carefully and make sure no wires are wearing or tearing, and that no screws are coming loose, etc. Having a solid machine that you know inside and out is more important than anything at this point.
In the middle school division, politics plays a big part in who picks whom for the alliances, so I wouldn’t fret too much over what your capabilities are at this point. Just do your best, meet some new people, and have fun at the event. 
I don’t know the exact percentages, but if I had to guess, I’d say that probably 93.7% of robots will be able to score cubes, 76.4% will be able to score sky-rise, and 25.6 will be able to score both.
Let’s fix that: About 95 percent should be able to score on floor goals, 75 percent should be able to score skyrises, about 50 percent will be able to score them well, about 30 percent should be able to score cubes well,about 5 percent are so overpowered they’d be finalists in HS division, and about 2 percent manage to get themselves disqualified.
That should work.
In all seriousness, though, from here in Michigan it was pretty obvious that the Skyrise builders were going to worlds, but the good cube teams is what put some teams over the top and others to be sad about being this close to World Championships. (sorry 7580C Minotaurs).
It’s not a great time to start working on a skyrise section autonomous. Depending on how good you think your robot is at cubes, you should probably be aiming to be picked as a second or third by a high-performing skyrise team. Film your robot doing cubes well - the more you can film in one continuous shot, the better because it makes it harder to cherry pick good takes.