How can be performed upgrade from 14.04 to 15.10? Is it enough to replace "trusty" as "wily" in sources.list and then run sudo apt-get update && sudo apt-get dist-upgrade?
You can not skip normal Ubuntu releases. You can upgrade one version at a time, which means you have to through 14.04 to 14.10 then 15.04 and finally 15.10. Alternatively you can upgrade LTS to LTS. which means you can wait for 16.04 and upgrade directly from 14.04 to 16.04. Modifying sources.list wont help at all.