Hosting SQL Server and SSIS/SSRS in same VM
This totally depends how healthy the server is SQL1,2008R2.

You will need to analyse first the usage of Databases, SSIS or SSRS and other parameters hosted on the server.

Also, what resources you have in terms of RAM, CPU, Disk(Raid levels) etc. available on the server along with how they are being getting used.

It would be a good start if you separate SSIS/SSRS on different server, assuming you have performed a load analysis on this server which might prompted you to think,in terms of for performance and scalability. Databases like to have a room of their own in terms of RAM/CPU (again this depends upon the usage of applications attached to it), thus other services like SSRS seems not a good choice to be hosted on same.

Generally, monitoring CPU, memory, paging and I/O on a server will give you an good indication of whether a server is getting a little too busy. You may have to do various calculation here and there and come to a conclusion which should answer you're question accordingly.

Therefore, it totally depends how the server is behaving currently and how it is expected to grow in future.