There are already a number of aircraft manufacturers playing in the next tier - Bombardier (Dash 8), Embraer (EMB 120), Fokker (F50) and others. I can't really see them ever building something the size of a 787 or A380, but I concede it could be possible.
Looking at existing manufacturers, I think Antonov may stand a chance. They already have the AN-124 and AN-225, which might be engineered into passenger configuration.
With regards to new players, I was reading an article about the Indian company Mahindra yesterday[1]. They have ambitious aerospace plans, already some exposure to the sector through their purchase of GippsAero[2], obviously with much smaller aircraft, but also are located in a fast growing market. The article mentions Boeing's expectation of over 1,000 new commercial airliners needed in India by 2020. Maybe this is your new lean, hungry company.
[1] http://www.flightglobal.com/news/articles/indian-automobile-...