Eastern Roman Emperor Constantine V had six sons - Leo IV, Christopher, Nikephoros, Niketas, Eudokimos and Anthimos. When Leo IV died and a regency under Eirene of Athens was instituted, a group of officials, including the Postal Logothete (foreign minister) and the commander of the Excubitors, conspired to place Nikphoros on the throne. IOTL, the plot was discovered and Nikephoros and his brothers were tonsured and later blinded and had their tongues slit. Nikephoros kept trying to claim the throne up until the reign of Michael I Rangabe (811-813), a total of six times.
What if the plot hadn't been uncovered and Nikephoros or one of the other brothers had been installed as regent or emperor? What would be the immediate and/or long-term effects?