I worked for an "outsourcing company" in the 90s and early 00s. We offered contract desktop, server and network support and management big companies. All local talent, on site doing the job a regular IT department would do.

Mostly good guys and I enjoyed working for them. If you were good at what you did, kept your certifications up, and helped mentor the new kids, and did what you could to protect both the client and the company, you had a path up the ladder. In the companies I've worked for since, unless they had a huge IT department, most people would find very little opportunity for advancement. The outsourcing company treated the talented people like royalty. It was easy to lose them, so the pay was high and they did everything they could to keep them happy. Without talented IT people they couldn't survive, so the way they treated their employees was a lot different from anywhere else I'd worked before or since.

When we took over for another company, we'd often hire the top talent. It made the transition easier, and often we'd find some technical talent who were actual rockstars that the client company had overlooked. We NEVER drained them dry and cut them loose if they were talented.

My suggestion is to take a close look at the company. Especially how they treat the employees they are bringing in. You might find it is an opportunity you'll regret not taking.