With all the information being dispensed by Matt Cutts and the Google web spam team, is link building soon going to be dead. In terms of not being a prominent factor in rankings?
Especially since you look at how guest posting is now considered a black hat tactic by Google's spam team.
Not by a long shot. Link building is still relevant, if/when done right.
It's a misconception that certain techniques should be completely dropped as soon as Google denounces it. It only applies to you if you don't balance out your strategy and chase quick wins by overusing that one tactic in a short period of time. If you do link building yourself, don't outsource and apply common sense, you are unlikely to get penalized.
The key to both successful SEO and link building is BALANCE. Here is a tip list:
1. Don't throw a lot of effort on it just once in a while - you want links to your site be added naturally and on ongoing basis without any spikes. Links eventually expire, so you don't want to experience a sudden drop from loss of links say 2-3 years from now.
2. Balance links between nofollow (often blog comments) and follow. You want to avoid too many easy-to-get nofollow links and ideally focus on getting more higher quality links.
3. Don't go after links from sites not relevant to your niche, no matter how easy they are to get. Context is most important factor for links. Panda penalized sites with a lot of links from unrelated sites.
4. Use SEO analytics tools like ahrefs.com to analyze your site's link profile - where they come from, what the anchor text profile is, etc. You want all data points to appear as even as possible.
Also, balance your link building with other SEO tactics like getting social signals (likes/shares).
I like this post on Top 5 SEO Ranking Factors in 2014