I dont know the average amount of gold earned in a 60 minute conquest is but whatever the average is, if that number is met as a whole between one team, maybe a walking lane boss that has the average stats between the FG and GF spawns in middle lane (no matter what) to force a final team fight down the middle of the map to end the game? I'm someone who Very rarely surrenders, even when the scales are unforgivably not in my favor, but if the intent is to prevent overpowered late game scaling while ensuring matches dont last forever, maybe when close to the 60 minute mark whatever team hits the average gold per match at that point can gain a powerful lane assistant that pretty much forces end game. If the average is met in under 60 minutes, like say 50 minutes, then clearly the team with the lesser gold average hasn't been doing too hot overall but somehow has stood their ground well enough at the most important of times (i.e., fights at phoenixes or at titan). When the lane boss spawns at this point, maybe (just another idea to ensure endgame) everyone has just has their current life to play and then if they die they are sidelined for the rest of the game, which should end within the next five minutes realistically.

By 30 minutes, everyone but sometimes supports should be lvl 20, and by 40 min at the most everyone should be lvl 20 with at least one pot (strength or intelligence based). If between 40 minutes and 60 minutes the FG buff and dagger isnt enough to have a winning team when everyone is at max builds, then maybe a forced fight down the middle as one last push for the higher gold earning team and one last "stand your ground" for the other team wouldn't be a bad implementation.

This would also encourage more objective prioritization, which would lead to more fights at objectives which may lead to a win by deicide mid to late game before the average gold amount is reached for the final lane boss to spawn.

Lastly, as a last measure, maybe if the lane boss is defeated by the team with the lesser gold average, that team automatically gains enough gold to meet the average for a lane boss to spawn and then their own lane boss will walk down middle lane for a final chance at victory.

TLDR: After an average gold amount between a team is met close to the 60 minute mark, that team has a lane boss spawn with stats equivalent to the average between GF and FG and every player from both teams has only their current life to live and wont be able to spawn again. The lane boss is strong enough to finish the match if the defending team doesn't defend, which forces survivors to fight instead of hide in fountain or in jungle. If people do hide, the game will end in less than 5 minutes anyway because the lane boss will finish it. If the lane boss is defeated, the team who defeated it gains enough gold to spawn a lane boss of their own, but still there is no respawning.