This time my focus is going to be on pointing out that this group is getting set up to actually stay around.
I have seen people point out that since A.B.C-xyZ did not debut and nothing came of the Chinese Johnny's group that was supposed to have debuted at Johnny's World that Twenty Twenty is not going to happen. I do not think those are the right examples to use, and honestly if a debut is announced there will be something to show of it in most cases. While A.B.C-xyZ did not debut we did get Sexy Zone (which is arguably the xy of A.B.C-xyZ) and Johnny Kitagawa himself stated that the Chinese group did not happen because of the political atmosphere between Japan and China. The latter is in no way going to be an issue for this group so if anything there may be some changes to the group, like with A.B.C-xyZ, but it will most likely come to be in some form.
Then there is the fact that there are already Juniors that have been placed in the group as potential members. As well as the announcement that we will learn more about the group, as in its members, when the next Johnny's World run begins.
If you look at the groups that have done the best at debut they are mostly the groups that were around as Junior groups for years before being debuted, such as KAT-TUN and Kis-My-Ft2. In fact Kisumai was around as a Junior group for about seven years before their debut, so having a group around for that long is not a great detractor. In fact being what will basically be a Junior group for seven years with the fact that their debut is actually being guaranteed can only be a benefit. As fans of the group do not have to feel anxious on whether or not the group will debut and only have to deal with members leaving the agency. So Johnny's can build a fan base for the group well before the group's debut, as I am sure there will be a core group of members that will get promoted, probably not much different that the Kami7 of AKB48. (The top 7 girls of the group popularity-wise that get the most work.)
If anything Sexy Zone proved that Johnny's needed to do more than just debut a group with some popular Juniors in it to get sales when it came to the FIVB groups. Even Arashi started out strong before dropping in popularity until they could build it back up. SZ though started low and are still fighting to rise. The switch to highlighting the older members over the younger members can be seen as a reflection of that as those are the members of the group that are the most popular and with a better schedule to be able to do idol work. Having Sato Shori move from being grouped with the younger two to the older two is also a sign of this as Johnny's has picked him to be the Ace of the group and they would want to make sure that he is with the more popular members of the group.
I have come to take the announcement of Twenty Twenty so far in advance not just something Johnny is spouting off to go back on but rather as future planning to make sure this group will not only happen but will succeed. Or at least at first as who knows how they plan on having this mega group managed without it being a complete mess. But with his age Johnny is probably only focusing on initial success as if he is still around for this debut he will probably be stepping down from being president of the agency not long after so long term success would not be his problem.