Measuring the sustainability of software products is sill in the early stages of development. However, there are different approaches how to assess sustainability issues of software and its engineering - including metrics with a practical orientation as well as more theoretical models covering software sustainability. As an example for one step in moving forward bringing existing approaches together, the paper presents a focus group study conducted to find out in which extent the quality attributes related to the technical sustainability can be measured by using existing metrics available at the MEASURE platform. Our first results show that the extent of measurability varies across the software development phases. Functional correctness, robustness, maturity, and testability are the most measurable quality attributes.