Having a blue chip FTSE100 stocks like Imperial Brands (LSE: IMB) can be a lucrative way to earn passive income. Imperial Brands’ dividend yield is already 7.8%. This means that for every £100 I put in today, I hope to make £7.80 in the future.

Not only is this yield nearly twice as high as the FTSE 100 average, but it is expected to enhance.

The tobacco products manufacturer announced today (May 15) its intention to enhance the interim dividend by 4%. This follows a 4% enhance in the annual dividend last year.

So with a high dividend yield and growing payouts per share, could Imperial Brands represent a passive income opportunity for my portfolio?

Unfavorable long-term market trends

In one word, my answer is no. But why?

Cigarette sales are dwindling in many markets, and this long-term trend looks set to continue. Indeed, first-half revenues were down 2.3% year-on-year.

This is despite the pricing power offered by the company’s brand portfolio. This means it may raise selling prices to counter falling volumes. Indeed, over the last six months, Imperial tobacco volumes have fallen by 6.3% compared to the same period last year.

But wait. Exactly the same risks arise British American tobacco (LSE: BATS) – and I have a vast stake in it. So why am I still bullish on British American but have no plans to invest in Imperial?

The short-term strategy belies the long-term challenges.

In one word: strategy. In recent years, Britons have been trying to move away from cigarettes. For now, they remain the lion’s share of its business, but the company has focused on rapidly growing its non-cigarette business.

In turn, Imperial has doubled its cigarette sales in recent years.

It sold its premium cigars business and scaled back its non-cigarette ambitions in areas such as vaping, instead focusing on gaining share in key cigarette markets.

For now, this could work (although falling revenues and earnings per share in the first half of the year might suggest otherwise). However, I believe that this does not position the company well in the long run.

No dividend is ever guaranteed

Why does this matter?

This may aid explain why the share price has fallen 9% over the last five years. On the other hand, the British and American share price performed even worse over this period, falling by 16%.

However, this also raises the question of whether Imperial Brands will be able to maintain its dividend in the coming years.

For decades, British American has raised its payout per share every year. However, in 2020, Imperial Brands’ dividend was cut by a third.

The latest results show declines in revenue, sales volume, operating profit and earnings per share. Net debt increased by 3% to £10.6 billion. This doesn’t look like a company in good shape to me.

Imperial continues to deliver solid profitability and has an attractive portfolio of brands. Cigarette sales are dwindling but remain significant.

However, I don’t like the risk that Imperial Brands’ dividend will be cut again in the future, as it was four years ago. I have no plans to purchase.