It would be not easy to generalize, whether they all thought that they could keep it or not. But especially in the 19th century there are some governor generals of India that expressed concern over the administration of the colonies.

The East India Company was making losses due to the wars that were being fought to make the Indian colonies safer. However, every time the East India Company finished fighting a war, it bordered to new "enemies" which required war again. Now Fighting a war is very very expensive. The profits that were made in India just couldn't cover the costs of the fighting wars. Especially after the 1857 mutiny in India, the British were more suspicious of the soldiers in India, that was mostly made up by natives.

Some of the administrators that were working closely with or in the East India Company, were not that optimistic about keeping India as a colony for a long time. 1874 the East India Company was defunct and India was placed under direct British rule. But the EIC had already left a big mess in India. Also in the beginning of the 20th century (1915) Gandhi appears with his freedom movement and also around the time WW1 begins. With that much debt it was impossible to keep the colonies intact.

Pati, Biswamoy: The 1857 Rebellion

Lord William Bentinck, Governor Madras, to Lord Castlereagh, President Board of Control Oct 18, 1804, Correspondence, Nottingham University, PwJb 772, pp. 272 ff

Minute of Lord Harris, Governor of Madras, 16.6.1854, Tamil Nadu State Archives, Revenue Consultations, pp. 4212-18

Ps. If you have questions, please feel free to ask. I will try my best to answer them.