Hosono has been judicious in his choice of words and is not tipping his hand at all. He is definitely staying within character, a character that has enabled a steep yet steady rise up the political ranks without making any enemies as far as I can see. (Hosono could easily have been Ozawa’s first choice to replace Noda had Ozawa not bolted with his faithful followers.) Indeed, if there is anything that can keep him from tossing his hat into the ring, it is his apparent aversion to confrontation. Look to him to announce his candidacy in a couple of days at most, or deliver a ringing endorsement of Noda.
The immediate political consequence of a Hosono victory over Noda would be a snap lower house election at the earliest point possible, before the usual initial jump in the polls wears off for a Hosono Administration. Common sense says that the DPJ will do better under him than Noda in the general election. Policy-wise, though, it is hard to see anything different between the two, particularly since the election outcome is highly likely to be an LDP-DPJ coalition.