the Liberals will gain in countries where they are more pro free enterprise, but the left leaning Liberals won't
Um, no. The poster boys for right-wing liberals the German FDP will be reduced to a microparty, as will the UK "Orange Booker" Lib Dems. In the Netherlands the pro-business liberals are desperately unpopular, while the left-wing liberals D66 are on the ascent. There is a significant chance that the Italian right-wing liberals won't even be in parliament and the right-wing liberals in Sweden are fairly unpopular at the moment. The only significant bright side at present for right-wing liberals is NEOS in Austria...
My following of European politics has generally shown the right has on average being going up each election round and the left down. Now much of the gain on the right are right wing populist parties like PVV, National Front, FPO (although they may have peaked and be declining), UKIP, AfD, True Finns, Golden Dawn etc. It seems those parties tend to do a better job of picking up former left wing supporters while the centre-right are able to hold their ground. Generally hard right parties tend to do best when the economy is struggling thus blame the EU, blame immigrants, while are weaker when the economy is doing well.
I
understand what you're saying, but you're relying
way too heavily on fancy guesswork and extrapolation based on previous elections, all the while ignoring national trends. If PES manage to go down in seats, I'll eat my shoes. The 2009 elections were awful for pretty much every centre-left party in the continent. So bad that even Hollande's PS probably will stay the same. Apart from PASOK's coming obliteration in Greece, and a smattering of Labour parties in unpopular coalitions; not many Labour parties even have room to head backwards. It is the centre-right that are easy pickings now - especially in Sweden, Portugal, Italy, the UK and even (weirdly considering circumstances) France.
In the UK and Germany, UKIP and AfD mainly draw wounds from the Tories and CDU respectively; the True Finns steal votes from
every single Finnish party (see: last election) while GD voters mainly steal from previous populist right groups like LAOS. The left are less vulnerable at this moment in time than the right.
And you can't deny that, much to establishment sorrow, pro-EU business liberals (think Rutte or Clegg or Bayrou or Monti or Westerwelle) may as well be terminal.
