In his research, "21st-Century Talent Spotting", Claudio Fernández-Aráoz shares how talent was assessed and placed across different eras.  His conclusion is that in today's day and age, potential to adapt and grow into complex roles and environments, is the key ability that a CEO or executive management of a firm should be assessed against.  How to identify potential is what was enticing and I'll expand on it further.
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Why Potential: Physical attributes were the key differentiators in the early era, followed by logical and analytical abilities thorough much of the 20th century (2nd era), shifting to competency in the latter part of the 20th century (3rd era) and finally to the 4th era, where potential needs to become the focus.  The reason for this shift is needed because the environment is volatile, uncertain, complex and ambiguous (VUCA), where competence alone cannot serve as a sufficient measure of success. 
Scarcity of talent: Top talent will further become scarce due to globalization, demographics and pipelines.  As emerging vs mature markets provide the biggest potential for growth, both of these markets are vying for talent.  All these markets are searching for young leaders between the age of 35-44, yet by 2020 most countries will have workforce exiting due to hitting the retirement age. Lastly, most firms don't have pipeline to develop talent for critical roles in management.  These external and internal factors combined will create a huge talent void in the near future.
How to identify Potential: Claudio and his colleagues at Egon Zehnder, an executive research have created a model for assessing potential. It begins with mining the potential candidates personal and professional history, have open discussions, perform reference checks and look to identify 5 key traits. 
1. Motivation: It's an unconscious quality, with a fierce commitment to excel towards unselfish goals.
2. Curiosity: To Learn and Change.
3. Insight: Analyze and extrapolate to find new opportunities.
4. Engagement: Make personal connections and use both logic and emotion to drive vision.
5. Determination: Pursue challenging tasks and deal with adversities head on.
Retaining the talent: An organization need not just find the talent, they also have to take care of the talent.  Autonomy, mastery and purpose and three factors that energize top talent. Financials also play role, though keep the key talent energized will drive the talent to stay motivated and sustain their drives.
From a practical perspective, I would suggest reading the, Tours of duty: The new employer-employee compact, by Hoffman, Casnocha, & Yeh. To keep the talent, authors suggest creating a compacts vs contracts with the talent - at any level vs just focusing on management.  They suggest rotations every two years, something management consulting firms do effectively.   Overall, this does not mean that competence, experience and performance should be overlooked, rather they should be viewed in unison with potential.
Ref: https://hbr.org/2014/06/21st-century-talent-spotting
Ref: Hoffman, R., Casnocha, B., & Yeh, C. (2013). Tours of duty: The new employer-employee compact. Harvard Business Review, 91(6): 48-58. Retrieved from https://hbr.org/2013/06/tours-of-duty-the-new-employer-employee-compact