I agree that we need at least GB, Kofi, and Samba all eligible for next season. If Higgs and January are unable to play for next season, we need to be legitimately 3 deep at "big" to make a run at the tournament imo.
As for counting on players improving a great deal, too much can be unrealistic, but there may be a reasonable mix where enough players improve 'enough'. Say DaMonte and Tevian all improve somewhat, and Griffin makes a good leap in ball security and poise in hitting open threes. Also, there's what we will lose (AJ and AD). Improvements need to make up for that. In some ways, one could make the case that we're real close. AJ was held scoreless against Northwestern. If he sinks one 3 pointer, we win. If Kipper is halfway to form that he has been previously (scoring 20+ against Mich St.) consistently, maybe a few more W's are on the record. Perhaps a player like Kofi can both open up the court offensively and stem the other team's offensive effort, helping to quell the horrendous second half runs of the other teams and tipping more games in our favor.
While that is yet to play out, the best case is that Kofi, Ayo, Trent and the others can convince a difference maker like Patterson to join.
Fwiw I think Christian Brown is no longer an option. The crystal balls are indicative of dominoes falling behind the scenes.