Whether to continue using VCL in your project, or migrate to an alternative depends alot on your requirements. The VCL framework is powerful and mature, with lots of 3rd party components, which makes it a good idea to consider. The alternatives have been improving rapidly, and to point out one as the ultimate choice really requires you to carefully consider your requirements, and validate the strengths and weaknesses of the different frameworks.
Considering that cross platform is on the road map, I remind you that so has 64 bit support been for quite a while. We might see cross platform support, perhaps on schedule, perhaps delayed as we have seen with many previous features. I want to believe its coming because I truly like the VCL framework, but I always have a natural doubt concerning the official road map of the RAD studio series - sorry David. ;)
If you've researched the different alternatives, and found VCL to be the best choice based on its relevance to your project, then I'd consider using the VCL framework, especially if it is a framework you are familiar with. Learning a new framework can - while often a good idea - be a time consuming job. So even though there might be a risk of the framework not being held alive (as will there be with any alternatives) you might save a lot of work staying with the familiar framework, if it is the framework that suits your project the most.
If you do consider going with C++ Builder and the VCL, you might find that the C++ Builder Journal is a valuable source of information, they have a relatively quite forum, but with some interesting posts in it, and some free hints on their website: www.bcbjournal.com.
Of course there is also the embarcadero forums, and this site, it may be a good idea to search the Delphi forums and categories, since it seems there are more active users on these, and by far more posts. One good thing though, is that conversion from Delphi to C++ in VCL related questions is quite simple.