Can this APP scale?

I am writing an APP that will use MongoDB as the database layer. I will describe the most intensive and common query of the APP.

Query:

  1. Query one or more collections for set a set of documents. The query, on average, will have 1000 filter conditions. All of the collections are indexed.

  2. The average number of documents returned from this query will average 1000 documents.

  3. Finally, for these 1000 returned documents, an aggregation step is performed to calculate a metric. Each of the 1000 documents will aggregate from, on average, 1000 documents. Then the result is sorted based on this metric.

If this is the most common and intensive query that the APP will need to perform, how many users do you think it can scale to?