In my view Ecuador has virtually no chance of qualifying for the next round. The Netherlands is of course the strongest team in the A group, but Senegal can also come pretty close. For example, they have Mane in the ranks, but there are still a number of strong players who play in the Serie A. Qatar may be the weakest country on paper, but it might surprise you because of the high ambition and the extremely fanatical footballers who have worked here for years and usually do not play in major competitions and/or tournaments.
I don't think that you have a good idea about the Ecuadorian team. They managed qualification from the toughest confederation, by overtaking teams that are ahead of them in FIFA rankings. Netherlands do have some talented and experienced players such as Memphis Depay and Luuk de Jong, but the recent performance is not up to the mark. And I don't trust Senegal, because they have a habit of losing crucial matches. Now coming to Qatar, there is a chance that they can be the dark horses. Qatar enjoys home advantage and recently they have performed well during the international friendlies.