Since the task might have multiple outcomes, here is one possible solution:

1. Define the problem and explain the potential causes.
The problem is that a key employee leaves our team which will cause friction, additional workload, loss of team efficiency and cohesion, or even motivation.
Potential causes for leaving the company may be a lack of opportunities for development (this is the most experienced team member and he would expect more), a job offer from a competitor, personal issues, willingness to change the work routine.

2. Select one of the causes as most probable and prepare at least two satisfactory solutions to this problem.
The most probable cause is the lack of development opportunities. Two possible solutions for this problem are: 1) form a new team within the company and put Eric in the leadership position; 2) empower Eric to make his own decisions for certain aspects of the work, provide more freedom and challenging tasks.

3. Identify the main criteria for making your decision (selecting a solution), compare the two solutions against your criteria and justify your decision.
The main criteria would be time needed to implement the decision; likelihood to retain Eric; cost for the company; effect on team performance.

Here is the comparison of the two solutions:

Based on the criteria analysis, we suggest making the decision to apply the second solution even though the first would have higher chances of success. The risks associated with forming a new team are very high and we cannot measure the outcomes.

4. Identify the type of the decision that you have made.
This decision has been made in uncertain circumstances, it is a nonprogrammed, tactical, and specific decision.