i personally believe 1 reason they wont start a eng dbo anytime is because if one were to open as of today .. almost immediately TW KR and even HK will become mass deserts meaning, the population of each version will decrease dramatically and they will instantly begin to lose money. no to mention it will make totally lame gameplay for the KR TW and HK natives. so postponing a eng dbo would keep the population of all versions dense (somewhat) and wasabi would have less problems to deal with as they continue to let us play blind (quest and content wise) all while taking our money (for those of us who cash)
another yet more relevant reason is they need to sort out who would even host the eng dbo , and work on translating all of the game which i imagine from wasabi's point of view is a huge unnecessary headache at this point in dbos history
i must agree if an english dbo did come hk and tw would die kr is already basicly dead