I'll try to keep it short; what if others could block the line of sight for Skye's ultimate, much like obstacles can?
I think this approach would fit well both thematically and mechanically. Firstly, Skye is there to cause mayhem, keep your cool, sacrifice your Fernando and her ultimate is no longer a supercarry. Second, since you can have hot-spots where the Payload is not surrounded by any obstacle - there are quite a few in each map - you are absolutely forced to either ult there for a - usually - guaranteed ace or play the odds and hope the enemy does not know that simply by running behind a pebble they can neutralize your ult, which makes it a rather binary decision instead of a powerplay you can utilize when the enemy has no tanks to block your ult, or are distracted by other threats.
TL;DR: Changing Skye's ult so that it can be blocked by other players if they stand in front of their team would fit both thematically and mechanically whilst nerfing it in the case the enemy knows what they are doing. She'd still be a "pubstomper".
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