For sure they won't change Trello to become like JIRA, and there is a little hope the JIRA UI will become more like Trello. So IMHO nothing to worry about.
I can see the clunky from Jira seeping into Trello over time. Especially if some of the devs weren't part of a package deal.
I like Jira but I understand why others aren't fond of it. I'd argue it completely depends on how you configure/use Jira. Administering it is annoying regardless though.
