Jeremy Siegel, professor at the University of Pennsylvania's Wharton School, warns that corporate earnings must strengthen in order for the stock market to sustain its current rally.

"I think we need an earnings acceleration if we really want to get this market moving," Siegel told CNBC. "But in the presence of a 1.5 percent 10-year [Treasury note yield], low rates, the Fed [giving] at most one increase [this year] and the dividend yield on the stock market being over 2 percent, people are saying, 'Hey, it's not bad being here.'"

Siegel predicts the S&P 500 headed above 2,300 this year, which means that the index would have to rise about another 6 percent based on Wednesday's level of 2,177.34, CNBC reported. Siegel is also looking at possible rallies in the Nasdaq and the Dow to take the markets higher.

Siegel believes that if a catalyst like earnings appears to drive growth, the Dow could beat its intraday record of 18,622.01, which the index set in late July, CNBC explained.

"We'll get over 19,000, that isn't much from now [and] it could reach near 20,000 if we get a meaningful acceleration in GDP and earnings growth, [along with] getting oil back towards $50 to $55," said Siegel. "That would revive the energy sector, which has been a big drain on earnings," he said.

"I don't think there's going to be that much deviation between the S&P, the Dow and the Nasdaq, [with] the Nasdaq [being] more tech heavy, [and] the tech sector has been doing well," he added. "That's really where the only real growth tends to be, but I think all of them are going to be up less than 10 percent this year unless we get a meaningful acceleration in the second half of the year." 

But other market pundits see a much darker immediate future for stocks. 

And famed market bear Marc Faber is actually growling even a little bit louder these days.

The editor and publisher of the Gloom, Boom & Doom Report, told CNBC that stocks are likely to endure a gut-wrenching drop that would rival the greatest crashes in stock market history.

"I think we can easily give back five years of capital gains, which would take the market down to around 1,100," Faber said, referring to a level 50 percent below Monday's closing on the S&P 500. 

"The fact is, the market hasn't really been driven by genuine buying, but by stock buybacks, takeovers and acquisitions, and market leadership has been narrowing. It's not that many stocks that have been making new highs. It's quite a narrow growth of stocks that have been very strong," he said.

(Newsmax wire services contributed to this report).

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