There may be exponential decline now. The exponent comes from how many people are infected per infected person and the period of time in which they do that.

If each person infects two other persons in three weeks we will see a doubling every three weeks. This was the exponential growth at the beginning. The question were - how long can this continue? - how many people are affected by that infection rate? Can we lower this rate?

Now we have the answer. Yes the rate can be lowered and in some districts the infection runs out of people. It may well be that certain burial practices lead to a very high number of infected people per burial. If that practice is abandoned the infection rate drops considerably. People who do not attend to these funerals and are not in close contact with infected living persons have a low chance of becoming infected themselves by accident - this we now know.

So currently each infected person infects one other person on average. This means if we continue what we do now, the disease will run out of people in the not too distant future and it will vanish.

I think ebola is too deadly to form a stable population of infected persons - therefore I expect that once the numbers drop back to the dozens that it will be eradicated. (Unlike for example HIV which allows people to live and spread it for years.)

One thing that could change the outcome dramatically would be if the ebola virus obtains other methods of spreading and a new strain with a much higher infection rate emerges. - While this is possible it seems that this is not likely.

Now, if you build a model, you must consider such uncertainties about things noone really knows unless there is better data. Therefore we can see the model as kind of a test like "What if we don't do anything?", "What if we don't manage to drop the infection rate to 1 by day X?" While the models are highly unreliable in predicting the future they can be very useful to interpret the past. For example it answers the question "Have we done enough in the last month to achieve our goal?". Not quite but it seems we're getting there.