Like most Cubans, Richard Soler cannot afford to travel. But, he says, he is still seeing the world, with each tourist he meets. He gives horse-drawn carriage rides on the streets of Old Havana.

When the expected wave of American and foreign investment arrives, he says, this Cuba, in a time capsule, won't wash away. "There is nobody like the Cubans. Not a McDonald's nor a Kentucky Fried Chicken is going to change Cubans. It's a lie."

Tourism is one of Cuba's primary sources of income. Since U.S. President Barack Obama announced that his country was going to normalise relations with Cuba in December 2014, it was as if a floodgate opened. In 2015, three and a half million visitors came to the long-isolated island, an increase of half a million from the year before, according to the Centre for the Study of the Cuban Economy at the University of Havana.

"Some people have this idea, I want to visit Cuba before it changes too much. I want to visit Cuba before the Americans overflow the country," says Ricardo Torres, an economist with the centre.

But Cuba is struggling to keep pace with the growing demand. On Tuesday, American officials are expected to sign an agreement with Cuba, allowing up to 30 direct commercial flights a day to the island - a first since the U.S. imposed an embargo on Cuba in 1960.

How the country will cope with the influx when shortages of certain goods are still a reality is unknown. As you walk around Havana, it is not unusual to see a construction crane in the sky or a building site for a hotel. But airports, hotels and the infrastructure of the country are in dire need of renovation and expansion.

Casaparticulars

There aren't enough hotel rooms and if one is lucky enough to book one, the rates keep rising. "It's a chain. Frankly, we'll suffer for some years ... because you do not change that reality in a few years," says Torres.

This may be the perfect moment for "casaparticulars". Long before Airbnb existed, Cubans were renting out rooms in their homes to tourists. They're called a casaparticular in Spanish, or private house.

Jesus Nordase is capitalising on the moment. In 1997, he and his extended family began renting rooms in one house. Now, they have three. He won't say how many rooms he rents. But he boasts that he's frequently fully booked and he's raising room rates.

"It's the best moment since we opened. One of the things we have is a lot of recognition and freedom of operation." But Nordase says the Cuban government still only allows each person to own one house. There is no organisation for owners of casaparticulars or formal co-operation. Perhaps necessity will expedite a change.

The people we spoke to are confident of two things. No amount of investment or influence by tourists will "contaminate", as Nordase put it, the Cuban identity.

However challenging it may be, they believe that the government will devise a strategy to expand development without overshadowing what makes the island distinctive. Whether it's next year or in 10 years, Soler told us, tourists are guaranteed to experience the Cubano spirit.