If catch and daily bonuses aren't enough to lure you back into playing Pokémon Go, maybe new monsters are. The SilphRoad has dissected newly added codes in the game's files and found references to shapeshifting Ditto and 100 Generation 2 monsters, from #152 Chikorita to #251 Celebi. Ditto has been in the game's codes for a while, but the team discovered a new "Transform" move meant for the critter with its own animation sequence. As you might know, Ditto is known for turning into the Pokémon it's battling in addition to its ability to breed with any monster.
Some codes found in previous APKs made it to the game quite quickly -- the buddy system, for instance, was found a week before it came out. However, Ditto has been lurking in the codes for quite a while now, but it still hasn't made its debut despite being a Gen 1 monster. So if you're wondering when the new monsters will start popping up, we're afraid you'll just have to wait for Niantic to announce an update.