No, the skates won't be a problem, if you can swim.
The most important thing in such a situation is not to panic. Remember that you can swim, and swim well.
If you can't swim well, then stay away from deep water no matter whether wearing skates or not. Even with a certified inflatable personal flotation device PFD I would not recommend going near deep open water if you can't swim well. If you have an expensive automatic inflatable PFD, the automatic trigger could fail and if you have the normal manual version then in every case you need to stay calm enough to pull the trigger and not swallow too much water in the time it takes for the PFD to activate. It takes several seconds until an inflatable PFD is inflated and takes you up to the surface. Plus the fanny-pack like inflatable PFDs, which is probably what you are going to end up with if you want it for roller blading, they still need to be put on over your head after they inflate. At first they are only attached to your hips and you can perfectly well panic and drown with your head 30cm beneath the surface.
And just to be very clear: Swimming well means you can do at least 300m in open water and you can do this at least in the breast stroke style and the front crawl style (head above water if need be) and you actually practiced this within the last year.
If you want to swim fast, of course the skates would be a problem. But you just want to get to land and no one is timing whether it takes you 30s or 2 minutes.
Your hands alone are completely sufficient to keep you afloat and slowly propel you forward. Crawl leg stroke probably works ok with skates, I imagine breast leg strokes would not work well, but still work better than not moving the legs, or butterfly kicks should work pretty much normally (but you wouldn't be asking this question if this swimming style was in your repertoire, I suspect).
Don't try to take off the skates, especially if you aren't very comfortable diving and swimming (this means you can do 300m as described above, but could not do several km). Trying to reach down might make your head go below water, which might then cause some breathing problem which in turns causes panic and then later drowning.
(certified professional lifeguard here, not much work experience, but I passed the tests just fine)