Oldchina has hit the nail on the head with the support issue. Many years ago IBM decided to enter what was then called the micro computer market place. The market at that time consisted of Zilog Z80 based machined runnng an operating system called CPM80. IBM and its clones stole the market because of improved performance and the support they could offer software developers. Later on, Apple nearly fell at the wayside because they could not offer developer support, despite having a far superior product. The same is true with airliner market. Airlines need the guarantee of (manufacturer) support for as long as they have an aircraft.
The support comes at various levels. The first level is training. Engineers and pilots have to be trained before the aircraft can enter the service. This means manuals, training aids, simulators and training staff. Next you need performance guarantees such as this aircraft can lift X payload from Y runway and fly N miles with such and such reserves. Then pricing and financing has to be arranged. Lastly spares and support will be required in service. The former have to be readily available and support in terms of "How do I fix this hole in the fuselage?"
None of these can be created overnight. And this is the minimum required. But given proper funding this is achievable within a few years. Then it comes down to the price/performance/aircraft disposal/support/etc. ratios that customer airlines are looking for.
Can they do it? Yes of course. But this is a huge undertaking requiring buckets of cash and many teams of well educated and trained staff who are expertly managed. After all, this new kid on the block will be competing against Boeing, Airbus, Bombadier, Embraer and they are well established in their markets.
We live in interesting times.