SegWit transaction P2WSH and P2WSH/P2SH cost respectively 6% and 19% more space while compared to P2SH, SegWit P2WPKH/P2SH cost 11% more than P2PHK.Alberto De Luigi argues that exchanges have no economic incentive in adopting SegWit as it increases the blockchain weight, does not save space inside the block size, and has no cheaper fees. Bech32 can help save up to 22% of space and would help in scaling Bitcoin if implemented with coordination among wallets. This could lead to 2mb blocks fulfilled with transactions using bech32, which have a 20% discount.While an agreement requires political matters, it is realistically possible to transition to bech32 as the default address for every wallet. The email is discussing the efficiency benefits of bech32 and its potential to improve scalability. The writer questions whether these benefits are only applicable to bech32 and not to other types of transactions. They also note that bech32 is not compatible with the majority of wallets, making it a hard fork. The writer suggests that a hard fork upgrade to bech32, combined with a 2x blocksize increase, could promote SegWit adoption while testing LN. They believe that this could be a more consensual and effective upgrade than a dynamic one. The email ends with a request for information on any specific upgrade plans for 2018. The links provided include articles on the costs and benefits of SegWit, as well as a Bitcoin-dev mailing list.