As quoted from Mousetimes:
Inside sources are telling me (along with many other sites for most of the information):
Fantasmic!'s last night was on Saturday before perhaps one of the biggest changes to take place. The reports are that there are going to be three big show changes:
1) Addition of the Jet Skiers going around during the Ursula scene. They will be Flotsam and Jetsam.
2) There will supposedly be a replacement crocodile.
3) THere will be a new dragon, aka "Bucky 2.0." She will be flown in within the next few weeks and will be installed by helicopter. She is supposed to be a huge animatronic with arms that will reach out and grab items and get even closer to the river to light it on fire.
Most of these changes will be announced on April 24th in a Disney Press Release along with changes to the Electrical Parade and the announcement of Magical.