Greece and Macedonia have a long running naming dispute, with Greece blocking entry of Macedonia into the EU and NATO. If Greece leaves the EU, does that mean Macedonia can join?
As @Bregalad already commented, leaving the Eurozone does not imply leaving the EU. That would be an even more dramatic and unprecedented event and there is no reason why Greece would want to do that (on a formal level, neither leaving the Eurozone nor the EU can legally be forced on a country, what other members or institutions like the ECB can do is be so uncooperative and make it so costly that the Greeks find themselves forced to take steps that effectively put them out).
There are even fewer reasons to think that Greece could leave NATO as a result. NATO is a narrow alliance based on specific concerns and Greece's geopolitic position hasn't changed (Greece occasionally flirts with Russia, emphasising their shared orthodox heritage, but it's only for show and Russia clearly isn't prepared to offer anything substantial). Besides, the US appears increasingly unsatisfied with Europe's handling of the crisis and certainly not in the mood to “punish” Greece in any way or let this impact their strategic interests (which is what NATO is about).
That said, and taking the question at face value, taking Greece out of the equation might help Macedonia move from EU “candidate” status (like Albania) to actual negotiations (like Turkey since 2005 or more recently Montenegro and Serbia) but would be unlikely to result in a quick membership. Beyond the naming issue, the country still faces many difficulties, e.g. a recent insurgency and chronic instability and one of the lowest GDP per capita in Europe (a bit over half that of the poorest current EU member, Bulgaria). If we go by the official assessment of the work to be done (status of the various acquis chapters), Macedonia is in worse shape than any other candidate save perhaps Turkey, more or less in the situation the Czech Republic or Bulgaria were in the 1990s! (For reference, the last new member, Croatia, formally applied in 2003, started with a much better initial assessment and joined in 2013; Bulgaria applied in 1995 and joined in 2007.)
Furthermore, many people grew unsatisfied with the consequences of the previous enlargements, the difficulties in implementing new policies and moving the EU forward, the imbalances and huge gap in income between old and new members and the political consequences of the resulting migrations, etc. so I would guess that everybody will be extra cautious regarding any future new membership.
Jean-Claude Juncker (who, as president of the Commission heads the institution that is most sanguine about expanding and deepening the European Union) tries to put a positive spin on all this but he basically acknowledged these problems last summer and explicitly said there would be no new enlargement under his presidency.
Instead the EU seems to be increasingly pursuing other forms of association (visa facilitation agreements with former Yugoslavian republics, customs union with Turkey, Eastern partnership, Central European Free Trade Agreement, Stability Pact for South Eastern Europe. etc.) and that's probably what lies in the cards for these countries for the foreseeable future.
Finally, Bulgaria also has some bilateral issues and went as far as using its veto to prevent Macedonia from entering the formal negotiation phase so they would also need to be appeased to go forward (the Commission has recommended starting negotiations with Macedonia five times since 2009 and the Council, which represents member states, blocked it, presumably at the behest of Greece and Bulgaria, which have a veto there).