Probably, since the main art for the game shows Mario on a grown Yoshi. But now that the baby Yoshi's have special powers, will you want them to grow? Maybe the adults will have 'em too, what do I know. --- All's fair in love and war, kid.
maybe.... the return of the power shells NSMBU style :D if that is true it will be awesome ujuju --- "He aqui mi secreto, que no puede ser mas simple : solo con el corazon se puede ver bien; lo esencial es invisible para los ojos."
^ Could just be for the demo, maybe they didn't finish adult Yoshi's yet. All it takes is changing a single variable to keep them from growing into adults for a demo. --- All's fair in love and war, kid.