I am waiting for another 2008, but I don't think that I will get

2008 is a very unique recession and severity in recent memory.  I made a statement in one my posts and I said that we will not see another 2008 in our lifetime.  The one recession more severity than 2008 was 1929.  That said, recessions are part of our economic cycles.  I am 100% sure that we will have one, but I don't know when.  Based on recent history, nine of last ten recessions happened during Republican Presidency, so you can figure out yourself.  

As for your 401(k) portfolio had 50% paper loss during 2008.  I would think that everyone's investment portfolios with similar market allocations as yours lost 50% as well.  The key here is age proper asset allocation.  That is why you will need to have total stock index fund with 1,000 to 2,000+ stocks in the fund, the risk is more diversified.  Stock is more risky than S&P 500 (500 stocks), S&P 500 is more risky than Total Stock Market Index.  As you are getting closer to retirement, you need to allocate more money to bonds or bond funds.  10%-20% in your 40s, 30%-40% in your 50s, 50% in your 60s.  Hope this helps.  Good luck.