Though it is too early to predict exactly how Google Instant will change the face of SEO and PPC but my first thought on it is what I am sharing with you today.
Google Instant's effect on PPC
1. Higher cost per click: As you type your keywords you tend to get results combined with Adwords Ads and this means ads get more and more impressions without any clicks resulting in lesser CTR for your ads. Though Google will considers an impression only if the visitor is on the results page for 3 seconds or more but I think this will to an extent skew the impressions data. I am sure the 3 second choice by Google is based on historical data Google of how much time it takes for user to click on any result but I still think 3 seconds is less time to analyze the results when Google instant is on. Coming back to the original point of higher cost per click I think as we will see CTR going down, quality score will also drop, resulting in higher cost per click cost.
2. End of Long Tail Keywords Game: PPC expert can always find keywords which have lesser competition but are much better targeted towards the niche but with Google instant user not only has the keywords suggestions but also has the preview of results. This means user is more unlikely to type something that is not suggested by Google instant resulting in lesser searched keywords to become lesser and lesser and I think it will get to a point where long tail keyword game ends.
Again this will mean more spend for advertiser. You can get lower per click easily for long tail keywords which has no competition but now advertisers will not only need to spend more on short and competitive keywords to get the same kind of traffic and conversion but also will see less conversion due to broad matching
Google Instant's effect on SEO
1. Toppers take it all: Apparently it looks like there is no effect of Google Instant on SEO but according to me there is a huge impact on SEO with Google instant, much bigger than PPC. It is one of those factors of Google where there is no change in ranking factor algorithm yet SEO experts can have nightmares.
If you are using Google instant you are likely to be using your keyboard and so you expect the results to be in your screen view and will not prefer to scroll. This means top three positions will become more important than ever and will drive away all the traffic giving nightmares to SEO experts who are not able to make it to the top 3 results.
One more bug (I presume it to be a functionality though) in Google instant proves my above point. Try setting 100 results in one page through Google preference. It does not work as expected and you can only see 10 results in one page all the time. This confirms that there will be very few people who would prefer to move very far down the page when Google instant is on and so Google is not keen on taking that functionality forward.
2. Sitelinks becomes major part of SEO: Sitelinks ( Sitelinks are links to site's interior pages and Google generates these links automatically, and you can only remove sitelinks you don't want from your Google Webmaster Tools interface ) which has always been a neglected part by many SEO experts will become a major part of SEO. You can see for yourself in the screenshot above that a user is very much unlikely to click on even second result.
To sum it up I think Google instant means more Adwords spend for advertisers and tougher for SEO experts. Do share your thoughts in comments below.