This question came to me after watching a docu about Gorbachev. What would happen if Yeltsin dies of alcohol poisoning after celebrating his election as President of Russia? Would it safe the Soviet Union as a whole? What happens during the coup in August 1991?
Provided that Soviet Union somehow avoided massive backlash caused by the August Coup, we are likely to witness Rump USSR with Baltics leaving (may be not even that, they were scared shitless by the Coup, after all) and everybody else staying within New Union with new Union Agreement being adopted. Georgians will btch about it very bitterly, but there're very few events they don't btch about anyway. Gorbachov stays President of the USSR, but his (and Unuin's government and legislature in general) capabilities are seriously limited by the new Agreement, granting more power to Republics (along the lines of OTL India or even more).
Economic situation is uncertain. My predictions vary from OTL Belorussian model (state ownership of resource industries, infrastructure and heavy enterprises, market in services and retail, rapidly extending to telecom, construction and manufacturing of consumer goods) to OTL Russo-Ukrainian (chaotic privatization with robber barons and a lot of "irregularities", to put it mildly).