Paul under 50 is concerning, but let's put things in perspective. Even Conway's internal poll had Rand at 47%, so I think we can assume that that's his floor in this race. In looking at the polls, 4 of the last 6 non internal polls have shown Conway at either the high 30's or low 40's, including the recent Rasmussen. If this new number is accurate, Conway would still be at 43%. The fact is, Conway is having a very hard time getting past that 43% in non internal polling, while Paul in the same timeframe has polled as low as 46(In the poll taken the first week of September, and likely the most inaccurate poll) And as high as 54%. He's likely below 50 now, but I think it's safe to assume he's in the high 40's, while Jack is in the low 40's. So he definitely has the edge in this race.
Right now, I'd say most of the undecided voters are probably conservatives who want to vote for Rand but have misgiving based on what they may have heard. Even with all the attacks, these voters are not really going to Conway, and I don't think they will. Come election day they'll either suck it up and vote for Rand or perhaps not vote at all, but if they're not sold on Conway at this point, I don't think he can win them over. Based on all this, Paul should win the undecided's enough to gain a victory of 52-54% or so, that's my prediction.