This is what I worry about in the US. I know the systems are somewhat different, but beneath it all people are people and the same everywhere. Support and "support" can produce profoundly different outcomes.
I don't worry too much about one party or the other eating itself from inside. Granted the entrenched two-party system limits the ability for a third party to rise quickly so that may cause some chaos. I recently visited a country that I've lived in for a while but haven't been there for 10+ years... many party names were completely unfamiliar but the institutions (parliament, executive branch, judiciary) still work just fine and nobody seems to mind that they need to vote for "democratic libertarian peasants union" or some shit like that in order to have their voice heard, so the multiparty system is more resilient in that respect IMO. But even in a two-party system something will fill the vacuum, maybe some faction from one of the parties, or some independents could grow a spine or something.
I do worry about voter disenfranchisement and disillusionment. I know I call them lazy lemmings every chance I get but the whole system kinda depends on them getting off their asses and voting. Maybe some chaos is actually good for motivation, not sure.