Both Mediatek and Qualcomm have no intention or plans for making a 8 core (octa core chip) for the mobile devices as they believe that the operating system and the applications of today are not ready for such powerful processors. The software and the OS are designed specifically for single quad-core processors, so it would bring no benefit to users with devices octa-core, and indeed in some cases it may cancel the benefits such has prolonged battery runtimes and so on. So, the Mediatek has released MT8135 quad core processor which will compete with the Snapdragon 600 and Snapdragon 800 CPUs.
The Mediatek MT8125 will be released in the Q2 2013. Specs are not yet available but we are pretty sure that the future is looking very bright the Chinese CPU manufacture. As of now, only Samsung, LG and Renesas have planned the launch of new octa-core SoC for smartphones and tablets.