If this expansion is set to last a year and they said there would be two raid tiers, that puts this tier ending in lets guesstimate around Juneish - assuming both have similar spans.
Based on what they are aiming for, I think its to soon. They also said if the next expansion gets pushed back there may need to be a third tier. If this were to drop in Jan giving us till lets say April to clear this tier, it very well could set up either another long final tier or a third.