The decision of the European Committee to realize one European Railway Area needs deployment of the European Rail Traffic Management system (ERTMS)in all member states. Application on new lines is less complicated than on the existing network. ETCS baseline 2 is operational (v2.3.0d).
The EC decided to develop Baseline 3 to include deployment for conventional rail as well. Many detected issues (CRs) will lead to a significantly improved Baseline 3 (v3.4.0). Next maintenance release v3.5.0. will be published in 2015.
Proper introduction of ERTMS and getting everybody on board still requires professional assistence.

Planning the future
The installed bases in all member states differ from each other. One migration strategy for all does not exist. Is your installed base end of life? Do you have plans to renew rolling stock? You need to realize part of a corridor? You want to built up experience first?

Many questions and aspects will complicate your decision making. Technical expertise and overview are necessary to guide these projects.

Migration to ERTMS / ETCS level 2/3
The ERTMS/ETCS is an ICT system. This demands another way of thinking than deploying classic signalling equipment. The deployment of ERTMS/ETCS cannot be compared with buying an ICT system for your business. Yes, you buy hardware, build in equipment in your trains and install a GSM-R radionetwork. The software shall be installed on your systems.
The big difference is that you join the group of European Single Railway Area users. You will adopt the harmonized rules in order to accept cross border traffic. Every decision you make shall respect the interoperability requirement.