While there didn't end up being any point/patch releases to Qt 5.8, The Qt Company is making good on their word for improving the release flow with Qt 5.9 and maintaining it as an LTS release.

Following last month's Qt 5.9.0 release, the developers are looking at releasing Qt 5.9.1 by month's end as the next point release. As of today is the soft-branching for Qt 5.9.1 with the goal of getting the update out on-time during June. They don't plan to delay the release for any additional fixes, since they anticipate frequent patch releases and thus Qt 5.9.2 won't be far out.

Details on Qt 5.9.1 via this mailing list post. Overall, Qt 5.9 is looking pretty solid and haven't heard of many complaints about it compared to some of the past releases.