So you mean it would be plausible that the international community would do essentially nothing if Russia invaded and annexed both Georgia and Ukraine? I can't see that as likely. At the very least, Russia would face a lot heavier sanctions than it has during the Ukraine crisis IOTL, and would get suspended or kicked out from a host of international organisations. Such larger wars would create heavy problems for the EU, for example, through the arrival of Ukrainian refugees in large numbers in Eastern member states, say, and both the EU and NATO would have to act in some way.
But if you mean that to avoid doing "next to nothing", "the international community", say the EU or NATO, would need to actually go to a shooting war with Russia, you might be right. I however think that there are a lot of things on the scale between "doing next to nothing" to "WW3".
I admit that "doing next to nothing" was too harsh a description of the West's likely actions. I would expect the West to do a lot if Russian tanks rolled into Kyiv and Lviv in 2014, but none of their measures would be likely to influence the course of events. I will rephrase it as "doing nothing of use," then.
Opunium asked whether Russia massacring Ukrainians would be likely to trigger action on the part of the West. I took it as a question whether Russia would be able to kill enough Ukrainians in the face of the Western response (I may be wrong in my understanding of Opunium's question, though). Massacres are stopped by wars, not sanctions, therefore any response other than war would count as useless under such circumstances. My thinking is as follows:
1. A shooting war between the West and Russia is clearly out of the question ITTL, so the occupation (and massacres to maintain it) will continue.
2. Heavy sanctions (like trade embargoes) are likely but not inevitable. After all, China and India would gladly buy Russian oil all the same, so embargoes will not work without blockade - and blockading Russia means war. Why keep an unworkable embargo on, then? Thus, even if one is instituted, it is likely to be lifted before long ITTL.
3. Kicking Russia out from a host of international organizations is not a heavy sanction in my book.
4. Arming and training the Ukrainian resistance is possible, but not inevitable.
Summing up, there are multiple plausible answers to OP's question:
a. Russia gets away with annexing Ukraine (and Georgia) ITTL. The West shuns it, but it doesn't help people fighting Russian occupiers, and Russia ultimately wins its war for good (like the USSR did in the Baltics in the 1940s OTL). If any embargoes are instituted, they prove ineffective.
b. The same, only with the West helping Ukrainians, but the latter lose even with Western weapons at their disposal.
c. The West helps Ukrainian guerrillas, they put this help to good use, and Russian occupiers retreat (like Soviet troops did in Afghanistan in 1989 OTL).