No,the 299 plan will continue to remain active and available for subscription,its not a promotional plan rather is a regular plan.The 349 plan is a new plan which has nothing to do with 299 plan.
299 was a promotional plan earlier where they used to provide 10gb/day @20mbps which was later modified to provide 1.5gb/day and 291 plan was introduced as a replacement and that is a promotional plan for new subscribers for first six months.
I am on 291 plan for more than 6 months and its still working.