What I think I would personally do wouldn't be too different. However, I think making statements like "It's the only decent thing to do for yourself and the others around you." is awfully harsh and judging to people who are actually in the situation. It seems to imply that they are somehow selfish by not ending their lives. Its important to remember that they are in the situation and you are not and therefore they have an understanding of their choices that you do not.
Anyway, its also relevant that most life insurance has a suicide clause.
My understanding is that voluntary withdrawal of artificial ventilation is not an uncommon choice for locked-in ALS sufferers, and does not count as 'suicide', but as 'death from ALS'.
Anyway, its also relevant that most life insurance has a suicide clause.