Gardening: If bacterial disease attacks my tree, what should I plant instead?

A recent column of mine discussed a bacterial disease, for which there is no cure, that has begun to infect the popular and widely planted southern magnolia (Magnolia grandiflora).
In response, I received the following email from Nick Kurek of Granada Hills.
“We hope to enjoy our ‘Little Gem’ southern magnolia as long as it lasts, but we need to plan for a replacement with magnolia disease on the way.  Can you please recommend something similar: evergreen (no messy leaf or