I like this change. I got Locket shielded once by my duo’d tank J4 jungle, and I didn’t even notice until he told me later. Seeing that giant dome would have been cool.
I wonder about how professional teams might use this item. Having one Locket on a backline Support could make a team hard to dive. Having a locket on a Vanguard like Jarvan IV or Maokai could also make their own dive easier while protecting their team afterward. Having both would be really powerful, and since Support and Jungle item slots are much more flexible, taking two Lockets could become viable or even meta.
Now that I think about it, only carries have inflexible item slots, and only four or five of them. Anyone could take Locket. Everyone could take Locket. The effective cooldown reduction from having just two Lockets would be huge, dropping it from 90 to 45 seconds. Every wave and a half, the team would get one back. This could really affect the ability of teams to teamfight.