<p>This paper introduces the concept of system of systems (SoS) and the challenges ahead to extend systems engineering (SE) to system of systems engineering. The birth of a new engineering field may be on the horizon - System of Systems Engineering (SoSE). A SoS is a collection of individual, possibly heterogeneous, but functional systems integrated together to enhance the overall robustness, lower the cost of operation, and increase reliability of the overall complex (SoS) system. Having said that the field has large vacuum from basic definition, to theory, to management and implementation. Many key issues like architecture, modeling, simulation, identification, emergence, standards, net-centricity, control, etc. are all begging for attention. In this review paper, we will be going through all these issues briefly and bring out the challenges to the attention of interested readers. This paper is based on a keynote presented at the ITQM International Conference, Bucharest, Romania, August 23-24, 2024</p>