Random thoughts.
Ashodin mentioned earlier the possibility of bringing bad Prophecy's land sacrificing theme, but instead doing it by exiling lands until end of turn. After thinking about it, I realized that this could actually be an interesting area to explore. The cost, "Exile an untapped land you control until end of turn," is technically less of a cost than tapping a land, since when it returns, it will usually be untapped. I'm not sure if it's possible to put it returning at end of turn in the cost instead of the ability, though.
With meld, a big problem is that you have to get two specific cards together. If it returns, I wonder if they'll go with my earlier suggestion to have any "left side" meld with any "right side", which they were testing out with New Phyrexia. The right side could have all of the text for the melded card, and it gets a boost if it has the correct name. Both sides can have mana costs affiliated with them. Left sides could have a cheaper meld cost as the card's mana cost increases. The right side's cost is based on the back. The melding requires paying both costs.
Phyrexian Bear - 1G
Creature - Bear Horror
3G: Choose a meldable permanent and pay its meldable cost. If you do, and you both own and control this creature and that permanent, exile them, then meld them into Unbearable Horror.
2/2
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Unbearable Horror
Creature - Bear Horror
Maro-Hating Hornet - 3G
Creature - Insect Horror
Flying
When Maro-Hating Hornet enters the battlefield, it deals 2 damage to target creature or player. You may search your library for a card named Hornet Sting, put it in your hand, and shuffle your library.
Meldable 2G
2/2
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If this creature is named Un-bee-lievable Horror, it has +2/+2 and flying.
5/5
Of course, there are a lot of moving pieces. I expect it will be really difficult to evaluate quality if they do it this way.