conditionals - Which tense should this be? "are to" vs "were to"

I've been doing some exercises lately when one thing struck me:

Miss Baiocci would, I am sure, be a real asset to your organisation, knowing as she does a great deal about the way a company such as yours operates. [...] If it were not clear that she is determined to move away from this area, we would try everything we could to keep her here. Assuming we are to lose her, I would be happy to know that she was being taken on by a company with a reputation such as you enjoy.

The "are". It is in accordance with the answer. The thing is, I thought it should have been:

Assuming we were to lose her, I would be happy to know that she was being taken on by a company with a reputation such as you enjoy.

I thought it was obvious at first glance that this is the Type II Conditional.

Which version is correct?

Thank you!

From Grammar and Vocabulary for Cambridge Advanced and Proficiency by Richard Side and Guy Wellman

Answer

The subjunctive were is used for a.) counterfactuals:

• If I were rich... (but I'm not rich).

Your text contains one example of the counterfactual in the sentence:

• If it were not clear that she is determined to move away from
  this area... (but it is clear that she wants to move away).

It is also used for b.) predictions about the future that the speaker believes are unlikely:

• If it were to snow tomorrow... (but it's high summer).

By this token, the words Assuming we were to lose her... can be regarded as implying a doubt that she will leave. But this doubt seems unjustified in view of the fact that she is 'determined to move away' and has applied for a job at another company.

In such a case the subjunctive were does not seem as 'correct' as the present tense (or Conditional 1, if you prefer to use these problematic terms). Nevertheless, there is nothing ungrammatical about were in the sentence.