It only makes sense that Google would eventually react to how searchers are adapting to the line of links they are used to by taking away the right bar. This is also further evidence of Google’s continued gravitation toward being a mobile-first search engine, since the right column of ads was not visible on mobile search.
While I understand why SEO professionals might worry, I don’t think the recent move to showing up to four ads above organic results will have a profound effect on organic search. The extra ad will only be showing on “highly commercial queries,” and there are several keyword types that remain ad-free or only have one or two ads on top, like e-commerce keywords with PLAs and no text ads, or long-tail keyword phrases.
Keyword research has always been an essential part of any SEO effort. With so much variation in SERP layouts and the potential to have up to four ads before organic results, strategic keyword research is even more important.
When determining which keywords you are going to pursue, search each term to see what kind of search results layout you are going to be competing within. I recommend placing a higher priority on keywords that have fewer ads between the organic results and the top of the page. (Naturally, there is a lot more to good keyword research than seeing how many ads are shown for a given search query, but this can be a tiebreaker between keywords when building an SEO strategy.)