His supporters, basically the GOP. Probably would have been DeSantis until people saw him. I don't think Haley would get the MAGA crowd. Maybe Scott would re-emerge?
We = Those who want to live in a democracy.
Take the person out of it and just think strategically. The election is in November. The sooner we give MAGA a reason they CAN move on (because democracy isn't enough), the sooner they can decide on the replacement and get it together.
Let's say tomorrow, Trump says something that makes it even more clear he has dementia. MAGA can get their next heir together. You stick to your current talking points and keep your base motivated by the threat to democracy. You wait until June to start hammering the dementia angle EVERYWHERE. Now MAGA is scrambling because they've all been hiding the dementia.
From a strictly strategic battle plan aspect, we want trump as the nominee as long as possible. Then blast him right before the election.