The future belongs to marketing specialists, not generalists.
If I were starting my B2B marketing career today I would think about becoming a specialist in one of two areas. These are areas of marketing execution and measurement that may seem narrow, but will be deep enough to be the foundation for a specialized career. Narrow and deep is the key to success. Be the one person at your company that really knows how to provide:
1) "Forensics". Be the specialist in how to data-mine the activity inside a B2B sales force automation system. Become your company's expert in turning those data into analysis, and then turn the analysis into actions on how to change the marketing activity that impacts all phases of that sales pipleine.
OR (not AND !)
2) "Measurement Agility". The traditional execution of a marketing program or campaign follows a long arc of time from concept to content to production to media execution to response and to results. Digital and social media are dramatically shortening that arc and this brings a world of opportunity for more agile measurement and response. Become your company's specialist on rapid-time, real-time measurement and adaptation.