Today Microsoft updated on their website that Nokia Lumia 635 will also come with 1 GB RAM now in selected markets. Lumia 632 is actually a LTE version of Lumia 630 and it sold very well during past few months.
There are very few devices left on the market with 512 MB RAM now. Because 512 MB is not a standard anymore and new apps come with at least a requirement of 1 GB RAM. Recently Microsoft announced Lumia 435 and Lumia 532. Both are entry level smartphones with entry level specifications but both come with 1 GB of RAM. So Microsoft is trying to make 1 GB RAM a standard. However, Windows 10 for phones is coming for 512 MB devices as well.
Microsoft updated the specifications of Nokia Lumia 635 on their official website as 512 MB or 1 GB RAM. And it is written that RAM varies with markets but specifically which market will get which version, is not cleared for now.