Google still makes most (~90%) of its revenue from search.
All the other products need to be[come] succusful for them to be considered alternatives for revenue.
No, it makes about that much from advertising, but "Google websites" -- mostly, but not only, search -- are only 71.3% of Google revenue.
Alphabet's 1Q 2016 10-Q: https://www.sec.gov/Archives/edgar/data/1652044/000165204416...
"Barely worth mentioning" because they don't even break out the $2 billion in quarterly revenue from non-advertising sources beyond "non-advertising sources" in financial reports, but in the most recent, the $400+ million increase in quarterly revenue in that category was primarily attributed to two sources -- increases in Play store revenue, and increases in "revenues from cloud and apps offerings for enterprise".
Its just hard for anything else to seem significant against the background of $18 billion in quarterly advertising revenue.
I suspect the fact they make so much revenue from advertising has actually blown tepid at the efforts to seek revenue elsewhere (e.g. is Youtube even profitable? Google Docs?).
I'm not sure it has -- I think (certainly this is true of the most recent quarter, but I think its a longer term trend) non-advertising revenue is growing at a faster rate (% increase/unit time) than advertising revenue. Its just that the fact that advertising revenue is so much bigger to start with makes the increase in non-advertising revenue seem insignificant in relation to overall revenue.
They have (at least) 4 large sources of ad revenue: search, adwords, mobile & youtube. If one dries up, the others may grow to compensate.