Colloquy says that the comeback of Diners Club continues, noting that US Diners Club cards will benefit from the global acceptance of Mastercard.

They do note the devaluation of Diners Club Club Rewards points vis a vis Southwest Airlines Rapid Rewards tickets:

Diners Club’s effort to make the card easier to use puts it squarely in the sights of competing card issuers and their airline partners. Southwest Airlines has already raised the number of Diners Club points required for a free ticket: Previously, Diners Club customers had to spend just $16,000 to earn a free Southwest ticket; now they will have to spend $24,000. By contrast, it takes $19,200 in spending on Southwest’s own Bank One credit card to earn a free ticket on the airline.

The piece doesn’t mention the devaluation for Priority Club conversions. Priority Club also partners with JP Morgan Chase/BankOne. It does speculate on what will happen to conversions with BankOne partner United:

Bank One, which recently was acquired by J.P. Morgan Chase & Co., also issues a United Airlines Visa that earns one mile for every dollar charged. As soon as Bank One’s United card is up against the more-flexible Diners product, the bank might pressure UAL Corp.’s United to give fewer miles out to Diners Club’s customers.

A similar devaluation of Starwood to United transfers occurred right after United entered Chapter 11 bankruptcy protection two and a half years ago, with BankOne providing $500 million debtor-in-possession financing to United.

While acceptance of Diners Club is a new huge benefit for the card, rewards devaluation combined with other changes (such as the end of two billing cycles to pay and an increase in the foreign currency conversion charge) weigh heavily against investing in a $95 fee Mastercard.

It will take the next several months for the value proposition of this card to work itself out. I’m personally waiting on the edge of my seat to see what happens to the primary rental car insurance coverage that currently comes with the card. If that goes or is otherwise meaningfully restricted, I’ll cancel my card. If not, I’ll keep it.