Only bugfixes go into Stable releases so 2.4 is not possible, it's highly unlikely Tin Can will be ready to be included in Moodle Core as part of 2.5 which will be released around June - If development picks up and it becomes really stable it might land in 2.6 core(dec 2013) but it's likely to hang around as an available add-on instead of being in Moodle core straight away.