The estimation of dhole numbers at 2500 individuals, although given by the IUCN, is a guessestimate at best. There is very little dhole-specific research anywhere within their range.
In my opinion, I would argue that dholes are: 1. more numerous than wild tigers (emphasis on wild tigers), and 2. less threatened than tigers - unlike tigers, dholes are not targeted nor valued by wildlife trade. In addition, tigers require more prey/larger prey to successfully reproduce.
In more detail:
Pakistan: tigers long extinct, dholes present in very low numbers.
India - Western Ghats: dholes present in numbers comparable to, or exceeding, tigers; in some reserves, like Parambikulam and Indira Gandhi Sanctuary considerably so
India - central: dholes present in Pench, Kanha, Tadoba, Nagzira, and patchily in forest remnants in numbers comparable to, or exceeding, tiger numbers.
Nepal and northern India: in the terai lowlands, dholes rare or absent, tigers present. In the Himalayas, tigers absent, dholes present patchily.
Northeast India: depleted prey base, tigers occuring at very low densities, dholes more frequent than tigers. Kaziranga and a few other well protected lowland areas where tigers reach high densities, show the opposite trend, with dholes absent.
Bhutan: dholes considerably more numerous than tigers.
Bangladesh: dholes absent, tigers present in the Sundarbans only.
Myanmar (Burma): extensive camera-trapping efforts, conducted at 17 sites throughout the country (Lynam et al., 2003), confirmed tigers at only 4 (23%), while dholes occured at 13 sites (76%). Out of 4099 camera-trap photographs, there were 34 records of dholes, and only 5 of tigers.
Thailand: dholes occur in good numbers in places where tigers have been extirpated, like Khao Yai, Khao Ang Rue Nai and Phu Khieo. In the few places where tigers are still present, the dholes also occur.
Cambodia: recent camera-trapping has confirmed dholes in large landscapes in the south, east, northeast and northwest, sometimes in good numbers (Botum Sakor, Virachey). No breeding tiger population has been confirmed anywhere in the country recently, and the last photos of tigers have been taken in 2007 and 2005.
Laos: tigers and dholes rare. Dholes surviving in more locations than tigers, but at low densities. Prey base heavily depleted.
Vietnam: no evidence of breeding tiger populations, dholes rare, populations highly fragmented, prey base heavily depleted.
Malaysia and Sumatra: dholes rarer than tigers
Java: tigers extinct, dholes present in several protected areas
China: very few tigers, but dholes surviving in parts of Yunnan, Sichuan, Gansu and the north
Russia (far east): 300-400 tigers, dholes rare
North Korea: no one really knows; tigers probably absent, dholes probably present.
The extirpation of tigers throughout most of their former range has actually benefited dholes - a phenomenon known as Mesopredator release. A number of studies and field reports from continental South-East Asia specifically state that dholes and/or leopards seem to have replaced tigers as the top predators in those ecosystems.