I think the problem with MasterCard is they are trying to market themselves as a bit more of a premium card but problem is American Express (especially in countries like the US, UK and Australia as acceptance is close to Visa/MC) already has a good chunk of the mid-range market and upper range market. Visa has the general consumer market and some of the higher range market in the US. MasterCard doesn't really fit anyway.
American Express in the UK has been taking quite a big share off MasterCard, with now 3 card issuers switching/switched to American Express for its credits cards and one bank trailing an American Express debit card (From Visa and Debit MasterCard).
It is very much market dependent though, MasterCard is doing really well in some countries (Mainly Spanish speaking). In Spain practically every debit and credit card (the small amount that exist) are MasterCard. It also has the Maestro debit card network throughout Europe.
It'll be interesting to see how every network is in 10 years time. I think American Express acceptance is going to grow quite rapidly with all the recent partnership with banks to acquire its network. The Discover/Diners network is another one to watch. I'm not sure how much growth Visa/MC is going to see outside of Africa though. Some markets like the UK, Sweden and Canada are already deemed "Nearly Cashless", so I can't see profits souring in these places for them.