I've worked for a couple of none aviation employers in the past that underwent expansion on a similar scale to Monarch. They just didn't have the resources to manage the expansion in enough detail and expanded into markets that were not profitable. When economic circumstances caused those markets to reduce in size they downsized, reducing staff on a grand scale.
If, I was offered the job, I'd probably take it. However I'd do it on the basis that I'd have a 50/50 chance of being fired within 2 years and wouldn't pin a mortage or anything like that around a job at Monarch. If it worked out though, it could be nice, but to start thinking about time to command and that kind of stuff is premature.
My gut feeling about Monarch is that they need to downsize and concentrate on improving margins, not expanding to increase revenue. So, good luck to those that get the jobs, but for goodness sake, go in with your eyes open, understand how risky the expansion is and have a plan B if it goes pear shaped.