IMO, you're cutting it REALLY close! Provided your flight is on time, you're still a few minutes deplaning and getting to ME pickup location. Then, you'll have to wait an unknown number of minutes until you load the bus and then depart. Then, you have at least 30 minutes to arrive at the hotel, but that's assuming you don't have any stops along the way. Best case, IMO, you're there at 3:30pm. Then you need to get settled in your room, change if needed, hop the monorail, go to the TTC, change to the Epcot monorail, get through security, walk all the way to World Showcase for your dinner. I think it will be really really close, if you make it on time.
Now, if your flight is delayed for any reason, forget it. You're not making it.