Could the Emperor of 30k Save the Imperium?

What i hear is people online often posit that only the emperor himself could save the imperium of man; people also seem to agree if the current emperor of mankind got off the golden throne the results would be catastrophic. My question then is if the golden throne could be stabilized without needing the emperor directly and he re-emerged as he was in 30k could this emperor of mankind save the imperium? Would he and the remaining imperial forces (Guiliman and Lion are active in this senario as they are towards the end of the indomitus crusade) be enough to fight not just the enemies the emperor fought way back when but the new ones the imperium has come to encounter (tau, tyrannids and such)?