Hope to be wrong though!
Atlassian's product range today includes unstructured (Confluence) and structured (JIRA) products.
Trello fits right in the middle. It has a myriad of use-cases[1] and is loved by the millions who use it daily.
[1] - https://trello.com/inspiration
Scott, CEO Atlassian
AWS applies the same trick with some startups in China (like they did with us) and I guess Silicon Valley as well. Bunch of free credits, free for a year. After you have your infrastructure with them it will be hard to switch to somebody else.
If we have built a product that is a (we think) great fit to the Atlassian customer base, who would we speak to in order to create a partnering arrangement with Atlassian? Does Atlassian do such business partnering arrangements?
It's not an addon for an Atlassian product so does not seem to fit to the Atlassian marketplace.
Also, the might include it or leave it separate. They might even include it and still keep it a great product.
My guess is they'll keep Trello running for a while as-is, and slowly rework it to become "JIRA Lite". It will likely have Trello-like functionality with JIRA branding, and some sort of migration path to the heavier JIRA for companies that have grown a lot.
Except for when you run into a bug that requires disabling of the Hipchat integration with Confluence... You'd think a company could make its own products work together better.
Slack has more speed, better integrations, better search, reliability. (For example, getting notifications on iOS.
I hate HipChat. Apologies to those that love it, but it's likely you never used both side-by-side during normal working days to compare.
So if Atlassian tried to put their mark on Trello, I have little confidence that it will still be Trello.