Samsung phones are great if you are into rooting and flashing ROMs. They generally have great performance hardware wise but Samsung software slows it to a crawl. If you don't care about that stuff I suggest phones with lighter software, such as Nexus phones and Sony phones to a lesser degree. Lumia 620 and HTC 8S are also good phones if you are OK with WP.
To answer the question, the feature phones are already going extinct. There are some Windows Phone 7 smartphones from Nokia that are really, really cheap (they have limited availability in Mexico etc. as far as I know). In a few years all phones will be smartphones.
Though I do agree that you can get smartphones for dirt cheap/free with contracts, I'm not really sure that the transition to all smartphones will be that fast. There seems like a decent sized market that prefer flip phones mainly to save money(data plan etc). Then there are people with 3/4g tablets and flip phones.