Well, of course the Dalai lama expresses doubts over the effectiveness of self-immolation...
Because the cause that the self-immolation is trying to serve is a lost cause: independence of Tibet.
Tibet is a Chinese province, it is and has now been for more than 50 years an integral part of China, in fact it has ties with China that are much older than 1959, deep ties.
A desperate act like self-immolation demonstrate that nothing else can be done at this point than a desperate act.
Buddhism is teaching us to not be attached, it is time to demonstrate that to the world, it is time for the Tibetan people in and out of China to show the true practice of Buddhism by taking care of the ethnic Chinese that are in the Tibet province.
Be a Buddhist host: demonstrate to your new neighbors in all cities and villages of Tibet the true practice of Buddhism: intelligent care, compassionate care, wise care.
If any Tibetan believes in karma, then they will easily understand that the best way for them to get respect and recognition is by giving it to others.
This does not mean "stupid" submission, it means cooperation, understanding, care and positive construction of a future together for the sake of peace now, and for the sake of future generations.
The CTA is not giving a bright example in this as they ostracize even their own people for practicing Dorje Shugden. I mean, how could they talk about peace with China when they foment war within their own community... that does not look serious, nor considerate or even intelligent.
There is no point in continuing the self-immolation.
it is a sad loss of life in terrible suffering for no effect at all.
And if the motivation was not the independence of Tibet but the return of the Dalai Lama to Tibet, well... I doubt that the Chinese Government would allow a Tibetan lama back in China if it shows that people are ready to immolate themselves for him... They would rather let him stay up in the Indian mountains, far away...