One of my clients has been dealing with a rep. management mess. We finally got it to where the ripoff report type sites were on page two and legit review sites were on page one.
For 6+ months they have had the 6 large sitelinks showing for their brand name just below the main site's meta description. In the past two weeks we noticed that they were replaced with 4 mini-sitelinks and a couple of internal pages are showing as standard results just below that.
My first thought was, CRAP who messed with the permalinks or screwed with something on the sites backend?! (hey, it wouldn't be the first time) After digging around, everything looked normal. Doing a few more searches for competitors brand names showed that it wasn't just them that had this happen. However, the results are very hit and miss. Some competitors stil have 6 large sitelinks and others are showing the mini-links and internal pages in SERPS.
Yep, one of my sites lost the mega sitelinks for "domain.com". Exactly as you described, I now have mini-sitelinks for the homepage as the first result, followed by two internal pages as #2 and #3 ..then facebook, google+, twitter, pinterest, youtube.
They might be changing that 7 vs 10 results thing. That seems to be a factor.