I think they can handle Beast Wars scale relative to WFC best by not being too strict with it, but rather just making the BW cast smaller on average. First off, Micromasters are way too small to really do the BW designs justice, and the disparity between them and the Ark transformers in the show felt exaggerated anyways. What about bringing back the scout/legends size class? Legends as in the size of potp Beachcomber? The smaller, simpler designs like Rattrap, Cheetor, and Tarantulas could work well at this size. The range of different sizes offered within a given price point (compare Siege deluxe Refractor to deluxe Ratchet, for example) could help with the bigger guys. This would also help the really large designs, like Optimal Optimus, Tigerhawk, and dragon Megatron look suitably huge next to the rest, without exceeding the leader price point.