There's a definite chance for a degree of surviving paganism in the Western Empire if the 392 rebellion after the apparent suicide of Valentinian II (r 375-87, 388 - 92) , a politically weak Catholic Christian (aged 21) under the control of his Eastern Empire-appointed commander in chief, succeeds. The main factor in long-term Christianization of an aristocratic social elite that was still largely pagan in the West, and thus 'trickle down' of the new religion to their tenants and workers, was the defeat of this revolt by the militantly Catholic Christian eastern emperor Theodosius I (r 379 to 395), the man who then legally banned pagan sacrifices and closed all the remaining pagan temples in both East and West after he put the western rebellion down in 394. (He also confiscated temple treasures and property and banned pagans from holding any offices under the state, which was the decisive 'nudge' in converting politically ambitious or job-seeking people, and after he died suddenly in 395 the policy was kept up by his sons' regimes long term in both East and West. His ban on pagan ceremonies extended to their pagan Games, which apparently included the Olympics in Greece as these were at a temple sanctuary venue and had sacrifices.) T had indeed sponsored official expeditions of state commissioners touring the East, especially Syria and Anatolia, in the 380s smashing up and closing down temples in the cause of 'destroying blasphemous idolatry' and his Christian allies in Egypt had sacked some leading temples there, smashed up their statues, and driven out their supporters by armed violence - ironic considering the similarity of C4th Christian to C21st Taliban and ISIS priorities and iconoclastic ideology.
The sudden death, suicide or not, of Valentinian, brother of T's much younger second wife, led to his commander in chief Argobast (a German mercenary protege of Theodosius) being suspected of killing him and so setting up a new emperor, his secretary Eugenius, and defying the East to save his own career . He also called in the still pagan majority of the Rome city nobility for help (the Western capital by this point was Milan, nearer the northern military frontier) and allowed them to stage pagan festivals and public sacrifices which T had encouraged V to ban - leading to the final flourish of public pagan festivities in Rome and the fury of the Papacy and Christian officials. The revolt was defeated in battle by Theodosius as he invaded the West late in 394 and its leaders killed - with the Goths, led by future sacker of Rome Alaric, in T's army. But if it had succeeded and T been killed, leaving his weak sons in charge of the East and unable to conquer the West, a pagan regime might just have survived - even if only temporarily - in the West with the pagan nobles of Rome its main support. Even if the much stronger East conquered it eventually, the new emperor there - if less violently Christian than T - could have been canny enough to conciliate the nobles by not banning paganism, just only employing Christians in senior offices like previous emperors had done since Julian the pagan died in 364. That way the nature and extent of Christianization in the West would have been different - and without militant Catholics running the East through the mid and late C5th too, the still numerous pagan local nobility in outer provinces and the pagan professors teaching at Athens university (shut down by Justinian in 529) could have kept going.
Not quite a 'state paganism' - the emperors found Christianity much more politically and ideologically useful and most rulers were hostile to any form of political or religious 'defiance' - but a far greater amount of religious diversity.