We have buff, baron, drake and execute indicators so we don't have to bookkeep and do math during the game.
So an option to see the enemy summonerspells/ultimates would be a huge QoL improvement.
This would make it clear too everyone to play around those timers.
This change would improve the quality of lower elo and make it easier for pro players so they don't have to bookkeep.
Season 10 can use this! :)
PS: This was suggested years ago too, but then ppl didn't even like the buff timers! Now that it has been in the game, people have learned to use and play around it which is core for league of legends today! So S10 can use an option to see enemy summoner spells/ultimates