Great analysis/discussion, eldruku. The market was likely underwhelmed by the proposed Cambodia acquisition, but the market probably has much less expertise and foresight than the DNA exec team. (From experience, that's a reasonable assumption, not wishful thinking.)
I have no idea of which property (or where) is potentially being acquired, but some arguments to consider:
1. As eldruku's analysis emphasized, some properties border on Thailand and therefore might have a dedicated flow of guests from there.
2. Cambodia's tourism is growing 15%-20% annually (link below for PDF of Cambodia Govt stats to Aug14). Vietnam remains the largest source of visitors (but no growth), but China is second and growing fast. Korea is a close 3rd, then Lao. Next down close together are Thailand, Japan, and USA. Point here is that Cambodia's tourism growth from high-income countries alone might drive casino growth, even with local competition. http://www.tourismcambodia.org/images/mot/statistic_reports/tourism_statistics_aug_2014.pdf
3. Vietnamese visitors will/might continue to drive Cambodian casino business (but not growth). The Vietnam citizen gambling law might have significant opposition or may take time to pass. Even if passed, some/many Vietnamese won't qualify for Vietnam casino access, so continue to visit Cambodia. Third, there may be tax issues motivating Vietnamese citizens to patronize Cambodian casinos (I'm not encouraging or justifying, just predicting).
(20min delay)